RF: RatingScale - refactoring

RF: extensive cosmetic refactoring for simpler code readability, minor efficiencies
ENH: new parameter 'acceptSize' (control width of acceptBox)
     good to allow user to set a size; looks bad if text spills over
BF: negative markerExpansion (for glow)
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