Adds in consistent events (always passing instance handle) for starting and stopping sounds in the sound driver. Adds functionality for hasSubtitle and getSubtitle by passing an instanceHandle.
Fix sound event instance handle soundNames
Simplify subtitle functionality
Merge pull request #252 from virtual-world-framework/subtitle-functionality

Subtitle functionality
Change reference to "this.nodes" to "this.state.nodes"
Remove deletedNode function from mil-sym view driver (taken care of in model)