Shared edit events (undo, redo)

[nlloyd]

Implement sharing of undo/redo events (proxy the commands in the menu and keyboard mappings).

[nlloyd]

Proxy mechanism is implemented for now, but deferring on the rest of this due to the difficulty in mimicking Sublime Text 2's undo/redo behavior (I get WHY it is implemented that way in the editor but it makes for a challenging situation when making a proxy for that behavior).

[nlloyd]

Personal notes on undo/redo in sublime:

• undo --> event appears to be ignored... out of sync actually
  • host-side need to detect undo/redo commands in command history and handle accordingly... inserts are handled weirdly thus require special handling
    • count characters from last insert command: send the count and looping undos on client-side
  • also on client side need to detect if possible when the buffer was first populated and STOP at that point... possibly on end-of-view event mark that point in the history