sms_sendtophone allows you to send SMS without confirming your number

sms_sendtophone_page() checks if the user has set a number but does not check if the number has been confirmed. Thus, users effectively have the 'send to any number' permission. This should be fixed. I've prepared a patch. This patch also includes my trivial fixes from #555922: Unreachable code: "You need need to setup your mobile phone to send messages" and #556002: Typo: repetition of "need" in sms_sendtophone_page().