Merge pull request #1 from pouriaMaleki/master

added option for delete by ctrl + delete
the bug with _Prop.jumpToBeginning() seems to be fixed
seeker's position now changes when focus area is shifted
WorkspaceManagerModel now emits an event when active workspace changes
renamed timeline to mainbox
GraphView now reacts to prop listing changes correctly
separated ActorPropModel from WorkspacePropHolderModel
MainBox is now an event emitter
props now get listed in the timeline
props in timeline expand and contract
WorkspaceList seems to be working now
some ux improvements
workspaceList has an entrance animation