BF + ENH: fixed timed keyboard events +++

1) BF: Fixed timed psychopy keyboard events bug caused by clock changes
in 1.77
2) BF: Also noted that same issue would occur for Mouse button press
events, so fixed that with same solution as for keyboard press.
3) ENH: Changed SimpleImageStim to use ubyte instead of float32
4) ENH: Added `GL.glPixelStorei(GL.GL_UNPACK_ALIGNMENT, 1)` to
SimpleImageStim  draw.
5) Added xinput_gamepad example to iohub_extended demo's. Beside's
showing how to use `xinput.Gamepad`, also shows how to add non-default
device to `launchHubServer` function all using default device config.
6) BF: Fixed bug in  iohub `launchHubServer` function that was not
allowing non default devices to be added correctly.
7) ENH: iohub config file documentation enhanced / example .yaml files
in docs are loaded from actual .yaml files.
8) ENH: Removed iohub configuration file *resource paths* support (nice
idea; bad implementation).
9) ENH (in progress): Started optional built in support for selecting
Condition Variable File as part of ioHubExperimentRuntime start-up
process.
Merge branch 'master' of git://github.com/psychopy/psychopy