Fix function name to better represent what it actually does.
More information in case of contact dict lookup failure.
refs #21 Allow to message phone numbers not present in contacts list.

You can now message any number using the same format of the contacts
list. E.g. "34555555555: hello"

Note the lack of "+" or "00" prefixes in there.
Fix message parsing when directed at someone.
refs #19 Fix private whatsapp messaging API.

The callback was expecting an incorrect number of parameters. It should now work again.
refs #18 Private whatsapp messages were not directed at the phone number as IRC nick (instead of actual IRC nick).

This should fix all of the issues with private messaging through the bot.