history: tbody: id given ("#table-body")
history cleans without reloading page
fixed issue #5: prevent negative spikes count
fixed issue #1: shorten button for level
fixed issue #2: snap to angle-feature (prevent by pressing cmd/ctrl)
modals are dismissable by pressing ESC
spikes count limited to >=1
Merge branch 'master' of https://github.com/papayafiction/triangula-leveleditor