BF: disable pyglet debug_gl option

Moved the " pyglet.options['debug_gl'] = False " statement to the start
of the visual.py module so that pyglet detects the change and uses it
during runtime.
ENH: time and clock changes. See Issue #286.

See Issue #286 for details
Merge pull request #285 from isolver/master

BF: Disable pyglet 'debug_gl' option prior to any other calls to the pyglet package.