ecere/gfx/drivers/OpenGL: Shaders migration -- Initial Take

ecere/gfx/drivers/OpenGL: Shaders migration -- Initial Take
- Modularized compatibility wrappers, moved out of OpenGLDisplayDriver.ec
   - gl3/immediate.ec: Immediate mode transition kit (glimtk*)
   - gl3/matrixStack.ec: Matrix Stack (glms*)
- gl3/glab.ec: Modularized out Array Buffer manipulation code
- gl3/wglDefs.h: Moved out WGL definitions
- gl3/egl.ec: Moved out EGL code (untested)
- gl3/shading.ec: Vertex/Fragment Shaders loading code and uniforms access (may also be adding materials/shading/lighting code here)
- OpenGLDisplayDriver: Now using extensions through glLoadGen generated modules (gl3/gl_compat_4_4.c or gl3/gl_core_3_3.c)
- OpenGLDisplayDriver (WIN32): Added code to specify profile and debug context with wglCreateContextAttribsARB()
- OpenGLDisplayDriver: Making use of glDebugMessageCallback() / GL_DEBUG_OUTPUT_SYNCHRONOUS to facilitate debugging
- gl3/fixed.frag: Fixed Pipeline Equivalent Fragment Shader (early start: texturing and color support)
- gl3/fixed.vertex: Fixed Pipeline Equivalent Vertex Shader (early start: vertex, color, normal and texture coord)