Rewrite core functionality to update attribute and props assignments (#96)

* initial commit updating custom element definition

* finished rewrite of core functionality

* update to core functionality - adding attributes

* account for default props

* bit of cleanup

* misc code optimization

* more cleanups

* update component props on attribute change

* small fix

* misc prettier change

* Update core.ts to remove attribute callback func

* only rerender if attribute changed and already mounted

* prettier misc

* syncing attributes and props and more core tests

* prettier formatting

* default prop values fix

* prettier fix

* remove unnecessary default props check

* add more core tests

* pass function name to attribute if set via properties

* misc change

Author: zerico007