OpenGL example: minor tweak for non-default font.

OpenGL/DirectX examples: support for international text input in UTF-8 + implement ImeSetInputScreenPosFn on Windows.

OpenGL example: added commented code to load custom font from filesystem

OpenGL example: comments on glfw window size vs frame buffer size.

Add support for Retina displays on MacOSX.

Fixes to allow clean 1-pixel thick lines in more use cases. PixelCenterOffset not the same as previously!

Minor text alignment

Added comments

Disable client state in OpenGL example after rendering. ...

Using the example code in another application that has other rendering
code can cause rendering bugs or memory access errors if client state
is not disabled.

Converted all Tabs to Spaces (git diff -w shows an empty diff)

Tidying up example applications so it looks easier to just grab code

Fixed scissoring in OpenGL example

OpenGL example now use the fixed function-pipeline. Code down by 120 lines.

Simplified ImDrawList system (samples are 20 lines shorter) + merged title bar draw bar.

Portability fixes to OpenGL example application (courtesy of djoshea)

Tidying up example applications

Tidying up example applications

Commented samples and shuffled bits of the initialisation based on user's feedback.

Added PixelCenterOffset for OpenGL/DirectX compatibility.

Added OpenGL and DirectX9 example applications