Enlarged OS X invisible cursor.

Fixes #206.
Added GLFW 2 particles example.
Plain port of particles example to GLFW 3.
Formatted particles example.
Replaced ad-hoc argument processing with getopt.
Cleaned up particles example.
Fixed uses of relative time for cnd_timedwait.
Added CLOCK_REALTIME to clock_gettime emulation.
Replaced ad-hoc extension loading with glad.
Removed unused bits of glad.
Added dependency section to readme.
Added native monitor handle access to native API.
Formatting.
Moved to XGrabPointer for cursor hiding.
Cursor mode cleanup.
Fixed link error introduced by previous commit
Revamped cursor mode test.
Merge pull request #217 from serialvelocity94/master

Fixed references to renamed function.
Removed extra argument
Merge pull request #219 from serialvelocity94/master

Removed stray argument.