add gtk3 experimental support in CMake

Fix CMake for GDL. Thanks to Samual Buttigieg for patch

update cmake for new files

cmake: - group source/headers per library (for some IDE's) - include headers with source listing (also for IDE's) - remove unneeded Find modules

cmake: turns out my recent commits (which I undid) were not incorrect, variables were set in subdirectories then used in the parent directory, where they were still unset. Fixing this broke the build because some files in the subdir were not compiling.

cmake: give all libs a _LIB suffix, workaround 'debug' being confused with cake keyword, and also dont mix up dor names with libs.

work in progress cmake commit: - cmake now builds all files that automake does but does NOT link yet - inlcudes nasty hard coded paths and libs (will replace once linking works)

Cmake: Fixed the extra -l in the link command, plus a add linking for all sub-libs of inkscape.

Cmake: remove header files from source lists

Cmake: more fixs for C internal libs

Adjustments to the lib directory Cmake files

add *.c to libcroco/CMakeFile and libgdl/CMakeFile

add CMakeFiles for libcroco, libgdl, libnr, libnrtype.