upgrade to XRegExp v2.0.0; lowercase filename xregexp.js
force lcase rename xregexp.js
cleanup XRegExp regexes (no functionality changes)
remove outdated XRegExp tests
use XRegExp.exec so named backref props available even when natives aren't overriden
Moving all dependency management into bower.json
Merge branch 'refs/heads/xregexp2'

Conflicts:
	build/build.js
	src/js/shBrushXml.js
	tests/brushes_tests.html
	tests/theme_tests.html
Deleted old files.
Fixed xregexp 2 related issues.