Updated README
Remove obsolete file
Year field of timestamp not properly filled for
system::get_current_timestamp method.

The year was not absolute on Linux, but relative
to 1900.
Correct headers for glew build.
Use header for glx extensions.
OpenGL display setup
Show and hide window, window event handling
Bad check in test for absolute year in system timestamp.
Merge opengl-linux into dev.
Various small fixes
- module config on Linux
- module suffix wrong on Linux
- window render device for OpenGL not completely initialized
Add travis CI yml