FTGL Code

FTContour: fix a memory leak in the outset building. SF #3302743.

build: use case/esac instead of AS_CASE to avoid depending on a newer
version of autoconf.

build: add a --disable-doc configure flag to disable building documentation.

FTFont: replace glTexEnvf with glTexEnvi where appropriate. Fix courtesy
of Bill Robinson <airbaggins@...>.

define new symbols on msvc builds as necessary

merge from brl-cad upstream in order to support cross-compilation (mingw efforts by Chris Thielen)

check for gsed in addition to sed

implement a quick check for __FUNCTION__ and __func__ based on whether the compiler can actually use one or the other at runtime. cache the checks and provide __FUNC__ for use via FTGL_CPP_FUNC.

add the compiler macros from BRL-CAD (http://brlcad.org) so we can use BC_COMPILER_AND_LINKER_RECOGNIZES() to conditionalize the testing of various compiler flags. this supports sf patch submission 3077204 from Dagobert Michelsen (dmichelsen), at least his first (0001) of four patches, that makes the build work with the Sun Solaris compiler.

credit Charles Huet (packadal) for the various compilation warnings he fixed that sammy applied in r1256.