Fixed renaming sprite breaking script references to that sprite
Added a semicolon
Removed a trace() statement
Prevented duplicate sprite names
Removed a trace() statement
Fixed renaming sound breaking references to that sound.
Made empty sprite name turn into Sprite<n> instead of <n>
Fixed updating references
Merge branch 'rename-sprite-update-refs'

Conflicts:
	src/scratch/ScratchRuntime.as
Made renameSprite/renameCostume DRYer
Implemented isSoundNameUsed and fixed a copy-paste error
Merge branch 'rename-sound-update-refs'

Conflicts:
	src/scratch/ScratchRuntime.as
Switched to using unused names when renaming costumes and sprites
Switched to translated defaults when renaming costumes and sounds