WICKET-663 enhance ichoicerenderer with id->choice object lookup
WICKET-663 enhance ichoicerenderer with id->choice object lookup

expose #getChoicesModel() and use it in IChoiceRenderer#getObject(id, IModel)
Merge branch 'master' into 663-id-to-choice-lookup
WICKET-663 enhance ichoicerenderer with id->choice object lookup

Improve the javadoc