feat(EventHandler) Add support for on-* style events

Fixes #649
Closes #729
style: code cleanup
feat(mustache): Move unobserved mustache attributes to the flush phase

Closes #734
chore(call perf): fix unfair tests

The wrapped called was doing an addition instead of only return a

Closes #733
fix(NodeAttrs): lazy init of observer listeners
style(events): code cleanup
chore(CONTRIBUTING): explain how to squash and copyedit

- Explain how to squash multiple commits.
- Copyedit.

Closes #740
refactor(forms): use errorStates and warningStates

Closes #736
Closes #706
Fixes #724