Add button to clear squad and start a new one.
Add ability to clone (non-unique) pilots.
Update README.
Merge branch 'feature/clear_squad'
Merge branch 'feature/copy_pilot'

Conflicts:
	README.md
	index.html
	javascripts/xwing.js
	javascripts/xwing.map
	javascripts/xwing.min.js
	javascripts/xwing.min.map

* Additional minor fixes to the behavior of the save buttons.
Credit where it's due.