fixed machinekit python module install directory
src/configure.in: fixed correct machinekit.ini path
src/hal/utils/halcmd_main.c: use default MACHINEKIT_INI if not specified
Fix Boost detection for newer Debian derivatives

The Boost library is now multiarched, so the Boost libraries may live
in e.g. /usr/lib/x86_64-linux-gnu.  The GNU autoconf-archive
`ax_boost_base.m4` tests don't account for this as of 13 Sep 2014,
[git rev. 3d67989][1].

This commit looks for `dpkg-architecture`, and uses the
`DEB_HOST_MULTIARCH` variable to generate another subdirectory
candidate for search.

[1]: http://git.savannah.gnu.org/gitweb/?p=autoconf-archive.git;a=blob;f=m4/ax_boost_base.m4;h=d7c9d0d3986e4dd4556dad84809d0f0fabdbac6b;hb=HEAD
Fix Boost link problems on newer Boost versions

On newer versions of Boost, reportedly from v. 1.50 on, the
`libboost_thread.so` shlib needs symbols from `libboost_system.so`:

    $ ldd /usr/lib/x86_64-linux-gnu/libboost_thread.so | grep boost
	libboost_system.so.1.54.0 =>
	  /usr/lib/x86_64-linux-gnu/libboost_system.so.1.54.0 (0x00007f801bbe1000)

This breaks the `emcweb` linking:

    $ make
    [...]
    Linking emcweb
    g++ [...] -o ../bin/emcweb [...] \
        -lboost_serialization -lboost_thread -lpthread -ldl
    /usr/bin/ld: objects/emc/usr_intf/emccontroller.o:
        undefined reference to symbol '_ZN5boost6system15system_categoryEv'
    //usr/lib/x86_64-linux-gnu/libboost_system.so.1.54.0:
        error adding symbols: DSO missing from command line

This commit adds autoconf detection of `libboost_system.so` and fixes
the linker command accordingly.

Additionally, it looks like at least newer Ubuntus and Fedoras have
dropped the Boost `--layout=tagged` build option, so shlibs with the
`-mt` component in their filename no longer exist.  On the older
Wheezy, these are just symlinks to the shlib without `-mt`, anyway, so
these can just be dropped.

The autoconf detection enables compiling for older Boost versions
where this may be necessary:

      ./configure --with-boost-thread=boost_thread-mt
Merge pull request #315 from kinsamanka/python_fixes

fixed machinekit python module install directory
Merge pull request #316 from kinsamanka/MACHINEKIT_INI_fix

MACHINEKIT_INI fix
Merge pull request #319 from zultron/boost-linking

Boost linking
Fix TCL/TK build deps in packaging

TCL/TK versions are bumped to 8.6 in Trusty, although 8.5 also exists.

Make packaging always insist on the latest version depending on the
distro and release to enforce reproducible packaging.
Merge pull request #320 from zultron/tcl-tk-pkg-deps

Fix TCL/TK build deps in packaging
Merge branch 'master' into fix_#317

Conflicts:
	debian/control.in