Graph#rebase
Snap to ways/vertices/midpoints when drawing (#240)

Also add anti-snapping behavior when option key is down.
Refactor operations

They're something distinct from actions. Actions are independent
of UI, operations are actions + UI (title, keybinding, modality,
etc.)
work towards using prototypes for entities
Move operation (fixes #536)
Remove unused DragWay behavior
better user icon style.
Merge branch 'master' of github.com:systemed/iD
Working more-efficient parentWays
Fix global leak
Pan map when dragging to pad. Fixes #534
adding operations icons.
adding css classes for operation icons.
Merge branch 'master' of github.com:systemed/iD
Micro translation framework.
button style improvements, modal positioning fix.
Fix tests with locale
Futuristic radial menu (fixes #548)
Futuristic radial menu tooltips
Add keybindings for all operations