use the CGAL triangulation with intersections enabled. attempt to fix issue #159
print only a single warning about intersecting vertices at dxf tessellation
, instead of spamming it over and over. also mention that it might be
due to intersecting lines, not just duplicate vertices (duplicate vertices
being perhaps generated by cgal's tessellator when it deals with intersecting
lines)
fix print statement
Capitalize 'duplicate'
Added difference test for something from nothing

The difference tests all subtract objects from an existing object but if
there is no existing object as the first argument the results are
inconsistent across Mac and Linux platforms.  Added a test to highlight
this condition.
fix bug where if $MXEDIR didn't already exist, build failed
allow 'mingw32' option. dont use OSTYPE. fix docs. allow NUMCPU multicore build
fix tabs in svg.cc
actually assign copyright to Marius + Clifford, to eliminate any
problems with Debian.
clarify mingw32 usage in docs & in 'print usage'
hand code html to remove qt cruft. makes it easier to change, and easier
to spit out to cmdline (eventually)
tidy up html for QTextBrowser. add shortcut for 'help'
move flattr image to right-hand side.
unify build scripts. introduce 'version checker' script. simplify instructions
Render all 2D objects 1mm high in OpenCSG/Throwntogether mode
Explicitly use UTF-8 as file encoding to avoid Windows automatically falling back to cp1252. Fixes #223
Bumped eigen to 3.1.2
Merge branch 'master' of github.com:openscad/openscad
do not use OSTYPE, its a read-only operating system variable
clarify README linux compilation