Compute hints once per argument. #performance
Update variable names for more semantics. #mania
The getValue() method is obligatory.
Add crate realdom!

A crate is like a lately-evaluated realdom. It ables to instanciate
realdoms that depend on holders (variables) without having any values,
only types.
Update exception imports. #mania
Fix API documentation.
Late construct realdom.

Also change predicate() for _predicate().