rework tree modification methods
make signal typing more flexible
update the base Item api
wip update to button
wip
wip
cleanup Item
move lodash to definitions dir
remove stale files
remove stale files
update event tracker
add a Widget class

The Widget class is a small subclass of Item which adds support for
events and signals.
add missing "get" keywords
update Button to use Widget

this changes the base class of Button and updates it to use the widget
event dispatching system.
wip
wip
cleanup the Size class
update docs
cleanup the point class
cleanup the Rect class