quadratic form based intersection
Squashed commit of the following:

commit bd8471f0f2c3f44f4aede271b911ac233d3cc4f6
Author: Dongxu Li <dongxuli2011@gmail.com>
Date:   Fri May 18 22:57:52 2012 -0400

    lc_quadratic solver: improved tolerance settings

commit 678506ff96a8c97baff3e0382ec8a505cde42b09
Merge: dfdea46 040b650
Author: Dongxu Li <dongxuli2011@gmail.com>
Date:   Thu May 17 20:51:59 2012 -0400

    Merge branch 'master' into dli

commit dfdea461619dff57d65a5a0f6eae42d96df9e8c6
Author: Dongxu Li <dongxuli2011@gmail.com>
Date:   Thu May 17 20:50:55 2012 -0400

    quadratic: debugging quad-quad solver

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Merge: 2ceedfb b5ad2fa
Author: Dongxu Li <dongxuli2011@gmail.com>
Date:   Mon May 14 19:51:46 2012 -0400

    Merge branch 'master' into dli

commit 2ceedfb6d7392c3df6ad473866933caf624250a1
Author: Dongxu Li <dongxuli2011@gmail.com>
Date:   Mon May 14 19:50:45 2012 -0400

    boost: file cleanup

commit a2174c4798ce26cea648df742b8b71374c281ec1
Author: Dongxu Li <dongxuli2011@gmail.com>
Date:   Mon May 14 19:18:58 2012 -0400

    quadratic: working getIntersection()

commit 8c5d1ab8a3e41fa1289a8f4df6a1e6f84ecd06b1
Author: Dongxu Li <dongxuli2011@gmail.com>
Date:   Mon May 14 19:05:31 2012 -0400

    quadratic: fixed move()

commit b58da60463de37f4df06eb6f9d319863c234459a
Author: Dongxu Li <dongxuli2011@gmail.com>
Date:   Mon May 14 06:56:36 2012 -0400

    quadratic: debugging for ellipse

commit d1703e3f13e344f46a7a352b1194e020ac94dabf
Author: Dongxu Li <dongxuli2011@gmail.com>
Date:   Sun May 13 23:28:14 2012 -0400

    print out quadratic, WIP

commit 7912c89971b16fe74190c7f13e8cbdad9f53c13d
Author: Dongxu Li <dongxuli2011@gmail.com>
Date:   Sun May 13 21:07:08 2012 -0400

    quadratic: working line-line intersection

commit c097673477809adb143cb98646a0230b16f1acb4
Author: Dongxu Li <dongxuli2011@gmail.com>
Date:   Sun May 13 19:38:52 2012 -0400

    hyperbola: fixed a segfault due to quadratic form

commit ca30c4aff4f8580fe76443d392861bbf88133f9e
Author: Dongxu Li <dongxuli2011@gmail.com>
Date:   Sun May 13 08:37:53 2012 -0400

    quadratic: implementation of intersection

commit f8922ab97fd694fe7400dc8e7031bd1a4f4a60fe
Author: Dongxu Li <dongxuli2011@gmail.com>
Date:   Sun May 13 07:27:20 2012 -0400

    hyperbola: solver implementation

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Merge: d4bd1db e6f9a6e
Author: Dongxu Li <dongxuli2011@gmail.com>
Date:   Sat May 12 07:46:38 2012 -0400

    Merge branch 'master' into dli

    Conflicts:
    	libraries/libdxfrw/src/drw_objects.cpp
    	libraries/libdxfrw/src/drw_objects.h
    	libraries/libdxfrw/src/libdxfrw.cpp
    	librecad/src/lib/engine/rs_ellipse.cpp
    	librecad/src/lib/engine/rs_entity.h
    	librecad/src/lib/filters/rs_filterdxfrw.cpp
    	librecad/src/lib/filters/rs_filterdxfrw.h
    	librecad/src/main/qc_applicationwindow.cpp
    	librecad/src/main/qc_applicationwindow.h
    	librecad/src/ui/forms/qg_dlgimageoptions.cpp
    	librecad/src/ui/forms/qg_dlgimageoptions.ui

commit d4bd1dbea839f6762b939a808fe4c85a2eb6ae94
Author: Dongxu Li <dongxuli2011@gmail.com>
Date:   Mon May 7 20:09:27 2012 -0400

    hyperbola: compiling issues

commit c68338c0187b6e9a5d43b933d9629276f78bb4e3
Author: Dongxu Li <dongxuli2011@gmail.com>
Date:   Mon May 7 19:41:35 2012 -0400

    merged master branch
    Conflicts:
    	librecad/src/lib/engine/rs_circle.h
    	librecad/src/lib/engine/rs_entity.h

commit 37208898b0ae8ba1bab1a6c7dbfbab2639cac445
Author: Dongxu Li <dongxuli2011@gmail.com>
Date:   Sat Apr 21 09:09:14 2012 -0400

    hyperbola: WIP

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Merge: 9bd1607 27a00d5
Author: Dongxu Li <dongxuli2011@gmail.com>
Date:   Wed Apr 18 20:23:07 2012 -0400

    Merge branch 'master' into dli

commit 9bd160770888f2f251eb19e295aee42279f85663
Author: Dongxu Li <dongxuli2011@gmail.com>
Date:   Wed Apr 18 20:21:52 2012 -0400

    added quadratic form for line/circle/ellipse

commit ee86aacaaf11a49a9155eb278bb4ecc22aea2612
Author: Dongxu Li <dongxuli2011@gmail.com>
Date:   Tue Apr 17 19:48:31 2012 -0400

    hyperbola: fixed building issues

commit e7c587b4bd5b37f7965deda064e92e6ebce9d528
Author: Dongxu Li <dongxuli2011@gmail.com>
Date:   Tue Apr 17 19:00:34 2012 -0400

    hyperbola: WIP

commit aedffcdb2752244ae519aaa67bd1aa447e44f218
Author: Dongxu Li <dongxuli2011@gmail.com>
Date:   Tue Apr 17 18:48:40 2012 -0400

    added hyperbola class

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Merge: 1d90925 6166f92
Author: Dongxu Li <dongxuli2011@gmail.com>
Date:   Mon Apr 16 22:15:46 2012 -0400

    Merge branch 'master' into dli

commit 1d90925795183eb5a42de0aac88a648e8449ba4e
Author: Dongxu Li <dongxuli2011@gmail.com>
Date:   Mon Apr 16 18:55:02 2012 -0400

    hyperbola: WIP

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Merge: 1f9aa4e 37da538
Author: Dongxu Li <dongxuli2011@gmail.com>
Date:   Sun Apr 15 23:46:29 2012 -0400

    Merge branch 'master' into dli

commit 1f9aa4e98e131c46ae7b06a2add715d2cad4b80b
Author: Dongxu Li <dongxuli2011@gmail.com>
Date:   Sun Apr 15 15:20:44 2012 -0400

    hyperbola: WIP

commit 0382382db17efe588048a45a63edeae0fc75aeb5
Merge: d3d01bb 4a40e7d
Author: Dongxu Li <dongxuli2011@gmail.com>
Date:   Sun Apr 15 08:51:57 2012 -0400

    Merge branch 'master' into dli

    Conflicts:
    	libraries/libdxfrw/src/libdxfrw.h
    	librecad/src/lib/filters/rs_filterdxfrw.h

commit d3d01bbb824f92451ed8267535c2c289503623ca
Author: Dongxu Li <dongxuli2011@gmail.com>
Date:   Sun Apr 15 08:48:16 2012 -0400

    hyperbola: WIP initial implement

commit 03aed73251a4ef443cdf4254fe9c56d3934a64d1
Author: Dongxu Li <dongxuli2011@gmail.com>
Date:   Fri Apr 13 11:59:11 2012 -0400

    Squashed commit of the following:

    commit ed096b45534a33fe491c4ce9e4f619def7a19348
    Author: Dongxu Li <dongxuli2011@gmail.com>
    Date:   Fri Apr 13 08:56:43 2012 -0400

        equation solvers: astyle

    commit 0800a110f81cd855960e30ecc69dc1065eeb67af
    Author: Dongxu Li <dongxuli2011@gmail.com>
    Date:   Fri Apr 13 08:55:20 2012 -0400

        equation solvers: file cleanup

    commit a711601086798c4005f4ce84a64698ad6529c25d
    Author: Dongxu Li <dongxuli2011@gmail.com>
    Date:   Thu Apr 12 19:23:16 2012 -0400

        circle tan2: recalculate centers when new radius supplied

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    Author: Rallaz <rallazz@gmail.com>
    Date:   Thu Apr 12 20:23:52 2012 +0200

        libdxfrw: added write image support

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Merge: b744050 166fcd7
Author: Dongxu Li <dongxuli2011@gmail.com>
Date:   Wed Apr 11 18:07:20 2012 -0400

    Merge branch 'master' into dli

commit b744050612f061f7a4aa5a9edd177248b42e9740
Merge: 38f4686 1772277
Author: Dongxu Li <dongxuli2011@gmail.com>
Date:   Mon Apr 9 22:20:32 2012 -0400

    test

commit 38f46860fbfa9723ed13ad094d2ef0daf504da2c
Merge: 55329fc d6a4b29
Author: Dongxu Li <dongxuli2011@gmail.com>
Date:   Sun Apr 8 08:19:23 2012 -0400

    trash

commit 55329fc640c570845dfd366ff3e2e3a80593e31b
Author: Dongxu Li <dongxuli2011@gmail.com>
Date:   Fri Apr 6 22:40:52 2012 -0400

    Appollonius: solution verifying logic

commit d48397c8a2bf369b66bda2afc165f87c9b6781a3
Author: Dongxu Li <dongxuli2011@gmail.com>
Date:   Fri Apr 6 19:31:50 2012 -0400

    Appollonius: verify solutions found

commit f2ff0167c1e22fa87a5a739151b7cba8d5d66fda
Author: Dongxu Li <dongxuli2011@gmail.com>
Date:   Fri Apr 6 18:31:36 2012 -0400

    Appollonius: debug selection conditions

commit 1031e351936975724e8f77c2a8909608e4048ab3
Author: Dongxu Li <dongxuli2011@gmail.com>
Date:   Fri Apr 6 18:24:42 2012 -0400

    Appollonius: fixed math in quadratic

commit 5645847a9f09446fe8bfb3e994688d98a1ac1ae2
Author: Dongxu Li <dongxuli2011@gmail.com>
Date:   Fri Apr 6 18:01:25 2012 -0400

    Appollonius: fixed a crash

commit 22002362030fff5e85471823acc747c70c7e564e
Author: Dongxu Li <dongxuli2011@gmail.com>
Date:   Fri Apr 6 17:26:42 2012 -0400

    Appollonius: initial implementation

commit 25ec3add0e51119921f4847baceae58ed5d5d494
Author: Dongxu Li <dongxuli2011@gmail.com>
Date:   Fri Apr 6 07:16:03 2012 -0400

    Apollonius: added icon
math: fixed a bug in angle comparison