Some investigation concerning update freezes.

Minor improvements to update routine.
Added ability to get application elapsed time.
Improved console callback functions and console behavior with registered
integer values.
Improvements into internal engine time management. Close #131

Also added flag EIF_ENABLE_PER_FRAME_UPDATE.
Added three new samples. Various minor bug fixes.

Added ability to tile texture in 2D, see EF_TILE_TEXTURE flag.
Added Basic 2D example.
Added Core Renderer and OpenGL example.
Added Render To Texture example.
Some minor IRender2D bugs and improvements fixed.
And other minor fixes.
Huge refactoring and lot of improvements and fixes into rendering subsystems (core, state manager, 3D and 2D). Added first real 3D example.

Fixed NAXScript exporter bug which caused wrong bounding boxes in
animated models.
Major cleanup and refactoring in CCoreRenderer and
CFixedFunctionPipeline, also some performance improvements.
Additional functions was added to the CStateManager.
Some minor performance improvements to CRender2D (all memcpy calls were
removed).
Added example "Low Level 3D".
MatrixBillboard bug fixed.
Bugs with wrong triangle front face direction (font and plane) for 3D
were fixed.
Improved materials handling for 3D.
And lot of minor thing including additional methods for engine
interfaces.
Added "Matrix Stack 3D" sample. Minor 3D subsystem fixes.

Close #65
All links renamed to dglengine.org