BF: removed some prints
BF: OS X crash from (non functional) win filter
Merge pull request #439 from isolver/master

BF: removed some prints
BF: staircase loops in builder were not using the min/max value settings
TESTS: further checks of optional dependencies (for jwp only)
TESTS: code clean-up for test_fitFunctions
ENH: Set volume in MovieStim (useful to mute sound by using volume=0)
Merge pull request #440 from frankpapenmeier/master

ENH: Set volume in MovieStim (useful to mute sound by using volume=0)
Merge branch 'master' of github.com:psychopy/psychopy
DOCS: updated changelog. Removed eyetracker component from Builder for release
FF: reinstated use of `guess` for curvefit