only add tokens of didBeginEditing if they were removed on didEndEditing

seems like you should only be re-adding the tokens to the token field on didBeginEditing if _removesTokensOnEndEditing == YES? otherwise, you haven't removed them so there's no need to re-add them. also, in this scenario, there are unbalanced delegate callbacks. willAddToken: gets called even though willRemoveToken: was never called (since the tokens were never actually removed). this is bad if youre doing any sort of validation on willAddToken: to make sure you're not adding duplicate tokens.