Implemented an action reducer to shorten action sequences before they're sent over the wire.

The most common case is a series of key presses (such as when using the 'delete that' command) being reduced down to a single action of repeated key presses.

I'm not expecting this to be blindly merged.  I did the work to try to speed some things up.  It's meant to be a bit of a springboard for other potential ideas.  But the basic gist is to reduce the number of RPC calls that are made when there are actions that can be combined together.