DOCS: adjust visual.* docstrings for better sphinx results
DOCS: more visual.* documentation tweaks, esp PatchStim -> GratingStim
RF: replace unittools.radians(), .degrees() with numpy functions

- could delete the tools/unittools.py package, but retain for backwards compat.
RF: remove some cruft from SimpleImageStim

- deprecated methods, etc
- inherit from MinimalStim
DOCS: visual.*Stim

- aimed at smoother online documentation
- remove references to deprecated stuff, like _posRendered
BF: sound tries note names before files; closes #543
RF & TESTS: refactor _SoundBase; add tests

- tests are for manual testing: not going to get called by Travis, and
  pyo and pygame tests can't both be run in same test session at this point
RF: revert SImpleImageStim
BF: launchScan needs updating to new RatingScale API
Merge pull request #555 from isolver/master

ENH: eyetracker validation. BF: launchHubServer
TEST, DOC: more coverage of emulator.py

- good coverage but not all logic is tested
- skip sound
TEST: stalled on Travis

- reorder to try to find culprit
TEST: skip emulator test that stalls
Added entry for gentoo installation
Merge pull request #556 from TheChymera/patch-1

Added entry for gentoo installation
ENH: Added mask for fixation cross

Created a transparency mask for "cross". Can be used for presenting a fixation cross in an easier manner.
Example use: fixation = pspy_vis.PatchStim(win=experiment_window, mask='cross', pos = [0, 0], size=1, sf=0)
Merge pull request #557 from suddhasourav/master

ENH: Added mask for fixation cross
Merge pull request #558 from isolver/master

BF: changed eyelink default cal colors
DOC: Added information for the 'cross' mask for GratingStim

Changed the docstring to include the 'cross' mask
Merge pull request #559 from suddhasourav/master

DOC: Added information for the 'cross' mask for GratingStim