Faux 'position: sticky' module 

Needed a simple js 'position sticky' module for a MPU test

Also, often we need access to the non-debounced window events (scroll, etc), so removed it from the mediator events, and moved the onus on the listener to throttle/debounce
Not quite, difference is debounce happens Xms after the last time it's fired, throttle happens at most every Xms. Both have leading/trailing options