Add a button
Replace discrete libraries with leap-widgets.js bundle
some cleanup
Add default mesh names
Draft pushbuttons in construct

Still need:
 - proper lighting
 - focus sharing between parent app and construct
 - hide cursor when showing hand
 - possible real focus events
Clean up tweening bug
Disable Leap interaction in HUD for now
[construct] Only show the cursor if no hands in frame
Fix issue where focus events would not be fired for newly loaded tabs
Set up construct HMD tracking
Oops, clean up some accidental changes
Add comment
Fix positioning of icon descriptions
Change lighting to brighten hand