Moved arrow asset
Bugfix: No initial sound explosion in choose scenario
Birdhero: Updated graphics + tweaks
Birdhero: Updated graphics 2
Merge pull request #23 from unholyhen/master

Balloon: New number representation system added
Garden: Less trampling of garden patches
New agent AI
Birdhero: coordinate update
Bugfix: correct sound object handling in addSound
Birdhero: Minor scale update
Merge remote-tracking branch 'upstream/master'
Difficulty C added. Rlusminus representation added.