Use om/transact! + *root-cursor* instead of swap! + app-state
Rename flense.render => flense.ui
Split off parse-tree helpers into separate flense.parse namespace
Implement walking movement
Implement basic history and undo/redo commands
Implement commands and keybinds for (barf,slurp)-(left,right)
Add sanity checks to (barf,slurp)-(left,right)