Set up fake x server for Travis CI
ENH: added a few convenience methods.
ENH: maximize painting window if size larger than desktop size.
MAINT: moved old DO.Graphics test programs to `examples` folder.

Stricto sensu, this program is not a test program.
WIP: adding real unit test for `PaintingWindow` widget.
MAINT: removed javascript sample program.

This file is irrelevant.
Attempted to fix build of DO_Graphics_example.
FIX: replaced image format `Format_RGBA888` to Format_RGB32.
WIP: adding unit tests for OpenGLWindow and GraphicsView.
MAINT: reformatted comments.
Merge pull request #31 from DO-CV/enh-add-graphics-unit-tests

[ENH] Set up GUI unit tests.