Catch OverflowError from Point.length()
Checking if view is alive before returning it.
Make sure we don't leave view boxes alive by doing a 'bridge' for the on the plot items. Also added warnings if proper cleanup wasn't done.
Update README to reflect loss of scipy dependency
Fixed multiprocess port re-use on windows
Corrected bug in multiprocess causing deadlock at exit
Multiprocess debugging messages now use one color per process
Corrected RemoteGraphicsView not setting correct pg options on remote
process

New debugging tools:
* util.cprint for printing color on terminal (based on colorama)
* debug.ThreadColor causes each thread to print in a different color
* debug.PeriodicTrace used for debugging deadlocks
* Mutex for detecting deadlocks
clean up debug messages
Rename Mutex module
Fixed multiprocess deadlock on windows
Added several utilities and debugging tools
Merge branch 'multiprocess-fix' into develop
Removed extra image window from VideoSpeedTest
PlotItem.showValues fixed (was not implemented before).
Fixes calculation of axis width/height in case values are not shown.
Added check for zero ViewBox width when calculating automatic downsampling ratio. (Prevents zero-division when downsampling is set before Plot is properly created and drawn within a container).
Fixed GLGridItem.setSize, added setSpacing
Merge pull request #58 from JNevrly/plotdataitem_downsampling_fix

PlotDataItem downsampling calculation fix
Disable weave by default.
Minor corrections to debug.Profiler
corrected SVG test, moved to its proper home
Cleanup / fixes:
  - Corrected isQObjectAlive for PyQt and older PySide
  - Warning messages are opt-in using pg.setConfigOptions(crashWarning=True)
Fixes to make crashing less likely on PySide

Merge branch 'clear_cycles' into develop