RF: use __setattr__ for PatchStim
Many changes, mostly to _BaseVisualStim and GratingStim:
- ENH: new setter-getter interface using "stim.attribute = value" syntax. Done by using a AttributeSetter decorator.
- ENH: more checking of parameter correctness (val2array)
- ENH: renaming of variables to better reflect internal vs. user-relevant attributes.
- RF: reduction of code redundancy
- ENH: this lead to a performance improvement of ~40%
Undo change of status to _status.
RF: docs for attributes in _BaseVisualStim and GratingStim.
ENH: for GratingStim. Reacts to autoLog attribute and added a autoDraw attribute.
RF: remove exec by introducing "_setWithOperation" function.
This should improve timing and code niceness :-)
DOC: more work on attribute documentation.
DOC: added documentation of attribute assignment.
Update unit tests for PatchStim to new-style setters.
DOCS: released 1.78.00 and changed download site to be sourceforge
Merge branch 'master' of https://github.com/lindeloev/psychopy

Conflicts:
	psychopy/visual.py