BRL-CAD bundles and maintains a number of external libraries and tools
critical to its functionality.

1.  Installed libraries

clipper		http://www.angusj.com/delphi/clipper.php	Boolean clipping - intersection, union, difference & 
								exclusive-or - on 2D polygons.  Used by Archer GUI.
libpng		http://www.libpng.org/pub/png/libpng.html	Portable Network Graphics library, used extensively.
libregex	http://www.arglist.com/regex			Regular expression library.  It might be interesting to try something
								like re2  PCRE here - this libregex isn't really maintained and
	                                                        has a nasty habit of colliding with Tcl's regex and/or system regex
								functionality.  Used by the red command, as well as search in librt and
                	                                        src/conv/proe-g.c
libutahrle							Utah run length encoded format - used by image processing tools, (?)
libvds		http://vdslib.virginia.edu			View dependent simplification.  Used for MGED/Archer level of detail control
libz		http://zlib.net/				zlib data compression library. Used widely - png and openNURBS 
								requirement, etc.
openNURBS	http://www.opennurbs.org			Non-Uniform Rational B-Splines support in libbrep, librt
poly2tri	fork of git://github.com/jhasse/poly2tri.git,	poly2tri is a constrained Delaunay triangulation library, and is
		which was in turn based on 			used during NURBS tessellation.
		http://code.google.com/p/poly2tri/
stepcode	http://stepcode.org				Derived from NIST STEP Class Libraries, with many modifications from
								BRL-CAD and other parts, this library supports STEP geometry conversion
tcl		http://www.tcl.tk/				Tool Command Language (TCL) - foundation of MGED's command language
tk		http://www.tcl.tk/				Graphical toolkit for Tk - currently used for most graphical BRL-CAD programs.


TODO - freetype, gct, libnetpbm, lz4, openscenegraph, PoissonRecon, rply, tinycthread


2.  Tcl/Tk packages
								The plan is to switch to using the full browser and its capabilities (like searching.)
incrTcl		http://incrtcl.sourceforge.net/			Object oriented extension for Tcl/Tk - all Archer GUI work uses these extensions
iwidgets	http://incrtcl.sourceforge.net/iwidgets		Part of the incrTcl project, used by Archer
tkhtml		fork of http://tkhtml.tcl.tk/tkhtml.html 	Used by MGED and Archer help systems.
tkpng		http://www.muonics.com/FreeStuff/TkPNG/ 	PNG photo image support for Tk - used by Archer
tktable		http://tktable.sourceforge.net/			High performing table widget for Tcl/Tk, used by Archer

