Trim all declaration values
No need to return the value from setNestedProperty
scope.$.get will find event handler functions (by adding their prefix and looking)

This now matches the behaviour in the object returned from snapshot.

This behaviour was required for the next expressions-related commit, so the expressions can find event handler functions, but it is nice that it improves the symmetry with the behaviour of snapshot()
README: document scope.$.get change in relation to event handlers
Expressions: statements in action handlers can return an event handler to invoke
Example of expression in event declaration returning the event handler to use