Escape dash.

This makes escape work in character classes.
build for last
Merge branch 'escape-dash' of github.com:xfix/Sugar into xfix-escape-dash

Conflicts:
	lib/common.js
	test/environments/sugar/regexp.js
Merge branch 'master' of github.com:andrewplummer/Sugar
Merge branch 'xfix-escape-dash'
build for last