Horizontal Grammar - Implement event blocks

[thisandagain]

http://www.scratchjr.org/learn.html#blocks

• Start on Green Flag
• Start on Tap
• Start on Message
• Send Message

Depends on #2

[tmickel]

Not doing start on Tap for WeDo. I also think we should have:

• On tilt (drop down for direction)
• Some kind of on distance - with numerical input?

[thisandagain]

Resolved in c1942bd