Implement nick completion (tab-complete).
Implement nick completion (tab-complete).

Including SHIFT+TAB to go backwards and the 'blink' css (which may need to be
factored out of the view). Mostly ported from Angular.

vector-im/riot-web,KentShikama/vector-web,vector-im/vector-web,KentShikama/vector-web,vector-im/vector-web,martindale/vector,vector-im/riot-web,pvagner/vector-web,howethomas/vector-web,vector-im/riot-web,Bitcoinsulting/vector-web,KentShikama/vector-web,neko259/vector-web,neko259/vector-web,KentShikama/vector-web,davidar/vector-web,vector-im/riot-web,vector-im/vector-web,KentShikama/vector-web,martindale/vector,pvagner/vector-web,vector-im/riot-web,KentShikama/vector-web,vector-im/vector-web,vector-im/riot-web,vector-im/vector-web