Polish Blocks.

Fix bugs with If/Repeater not resolving iterators correctly.
Also allow Repeater to accept simple arrays as the source.
Don't require a _spec in View.

This allows others to subclass View without using Blocks.
Allow binding events to child views.

Also make sure to resolve bindings against the proper scope.
RepeaterBlock now is more robust.

It can handle sources that are empty or simple values.
RepeaterBlock updates correctly with plain arrays.

Now if you setData a new array that is the source of a repeater, it will cause the repeater to re-render its children appropriately.
Fix #33

Allow repeaters to share a blockTemplate in nested repeater cases.
Merge commit '1fa133b1e5348edfd27f25549861020a24fea8ca' into fixeswithblocks

Conflicts:
	src/Block.ts
	src/View.ts