UI Infrastructure: Events

[bryphe]

Right now, for our examples like AutoComplete, we just bind directly to the raw GLFW / window events.

This isn't ideal, because for things like focus management to work, we need to control the 'bubbling' of events across the node 'hierarchy'.

We should implement a handleEvent method on our Node hierarchy, and add the following event types:

• KeyDown
• KeyPress
• KeyUp
• MouseDown
• MouseUp

These are events that we'd bubble through our node hiearchy, and then expose as handlers on the primitives / component tags.

[bryphe]

The infrastructure for this was implemented in #117 - closing in lieu of more specific / actionable work 😄