A bouncing - physics turtle
This turtle now has an init, not setup, and no longer uses RawTurtle
Wrapping import with try/except
Merge pull request #18 from dannystaple/master

A bouncing - physics turtle. An initial attempt at getting physics integration working
Added py2 to travis, and updated README
added disable_turtle ctx manager
fake 2.7 Tkinter too
stug mainloop
stub mainloop properly
Refactor TurtleWorld/PowerTurtle

 - no world parameter passed to callback
 - factored out RawTurtle specific __init__ stuff better
 - added _do_callback wrapper function for better subclassing
 - more docstrings
make random_walk look more like turgles demo
Merge remote-tracking branch 'atwd/master' into eval-demo

Conflicts:
	turtlepower/asteroids.py