GLMixer Code

Compatibility for OpenGL < 4.3 : glGetInternalformativ was used without
without being tested.

Disable Source editing action while its implementation is not reliable.

Various fix in Cpack Debian package generator.

Limit size of texture to system's maximum OpenGL texture size.

Spellcheck

Improved FBO compatibility issue for OpenGL version < 2.0 (power of two
FBO texture size).

GLSL 1.10 implementation of stippling (no warning).

Fixed stippling code to be compatible with GLSL 1.10,

removed dependendy on #extension GL_EXT_gpu_shader4

Fixed support for non-16bits-alined image width in RGB24.