Allow node.off(listener) and node.off(eventType) syntax
Better typing for event handlers

So far MouseEvent and KeyboardEvent are being used for the callbacks.
Add wheel() event

Uses the new W3C standard, no fallbacks yet, so support will probably be patchy
Add @useParentTemplate metadata, make it work in macro.

Had to add BuildTools.hasClassMetadata(metaname) also
Some updates to style.

Some of this stuff is actually working now, no unit tests yet.  Still
very open to changing things, so use with caution