Unicode throughout MegBot

[tsyesika]

To fix all the encoding bugs we have now and in the future I think we need to convert data when we get it in to unicode on all inputs and then when we write it out write it as "utf-8". I think the places we need to change are:

• Store (Library) - write to utf-8, read to unicode.
• Weather (the cache?)
• Seen (the cache)

Finally the input from the IRC. I think for characters we can't write to utf-8 we just drop.