ENH: added BaseVisualStim._updateVertices()
ENH: new vertices control working for BaseVisual and grating.py
ENH: new vertices control working for BufferImageStim
ENH: working on new vertices method for RadialStim (not working)
ENH: new vertices method for RadialStim and SimpleImageStim now working
FF: corrected vertex order so that orientation hack wasn't necessary
ENH: working on elementarray support of new coord system
EHN: new coord system working with ElementArrayStim

Moved the unit conversion function to tools module

Also fixed the orientation to work in the same direction as GratingStim. This
had been fixed with a hack before to alter the orientation during setOris()
but should have been fixed in the rendering routines instead.
EHN: new coord system working with ImageStim

also corrected buglet in Image demo
ENH: new coords system now working for text position

updated test images for text test suite
ENH: more efficient accessing of the posPix

We should only access posPix once because it's using a python property
which is 4 times slower to access than a normal variable.
ENH: MovieStim now supports new coords system
ENH: DotStim and ShapeStims all now using new coords system
ENH: Aperture and DotStim now support new coords system
FF: new MovieStim draw() method was corrupting color rendering of other stimuli

This was caused by the wrong texture target being left activated
FF: tools.monitorunittools.convertToPix() made more general
ENH: contains() and overlaps() and now use the new unified coordinates

They should now accomodate different units for different objects
event.Mouse has been given a `units` attribute (which reports the win.units)
so that it can also be used automatically in this system.
Merge pull request #474 from peircej/feature-refactorCoords

ENH: refactored coordinates system for stimuli