Fix for bad boost libraries

Get this error because of a search for a non-existent library on linux64
-----------
[ 69%] Built target tests-cgal
Scanning dependencies of target cgalcachetest
[ 70%] Building CXX object
CMakeFiles/cgalcachetest.dir/cgalcachetest.cc.o
make[2]: *** No rule to make target `/usr/lib/libboost_thread.so',
needed by `cgalcachetest'.  Stop.
make[1]: *** [CMakeFiles/cgalcachetest.dir/all] Error 2
make: *** [all] Error 2
[2]+  Done                    gedit openscad.pro  (wd:
~/git/openscad_unicode)
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Unicode support for strings

Add suport for using unicode strings in .scad files. Support iterating
across them/accessing them via [] and searching.
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Add GLIB (to build for test and normal build -- both with installed and
built locally development files).
Add support for unicode chars to length and search builtin functions and
[] for strings.
Added unicode testing functions.
Ad GLIB to library info page.