Trying to fix up merge with master
Experimented with music block colour and some bug fixes.
Initial skeleton of an undo/redo system
Add undo and redo to the context menu and make cut/copy/paste undoable/redoable.
Implement undo/redo for dragging, not yet fully functional
Merge branch 'master' into 250_undoredo
Merge pull request #378 from dannywils/master

Merge block preferences
Merge pull request #379 from dannywils/master

Use built-in element.classList functions
Fixed obsolete blocks in Breakout and added three new sprite blocks relating to edge of the canvas
Took out incomplete bouce off block so I can make a clean push
Changed movement direction to use a vector
Merged new block change with vector change, hopefully
Merge pull request #380 from apepers/master

Added three new Sprite blocks, removed some obsolete blocks from Breakout
add comment giving credit for the sprite code
Merge branch 'master' of https://github.com/waterbearlang/waterbear
updating dist files
fix for on key handler
Added bounce off block and fixed breakout
Forgot to update the breakout example in last commit
Merge pull request #381 from apepers/master

Added Bounce Off block, fixed Breakout movement vector issues, and tided up excessively long scripts in sprite.json