Add login and character map move functionality

[dracc]

This became quite a big change.

Changes proposed by this PR:

• Add login form connected to game account credentials
• Switch Account tab into Map Switch when user is logged in
• Add functionality to allow map switches for offline characters

Known problems

• JSON data in chardb->characters->entitydata lacks whitespace after a map move. Shouldn't matter, but I'm not sure how picky the cerealizer in SEGS is.

[dracc]

I've now confirmed that the client and/or server does not care about the lack of whitespace in the binary blob named entitydata.

But maybe, just maybe, we'd want to reset coordinates on city move, as moving currently often results in a need to use /stuck.

[dracc]

Todays changes:

• Favicon added
• character position is reset to [0,0,0] on city switch
• confirmation text on successful switch

[mobbyg]

Looks good. I can’t test now as I’m at work. But I’ll push this and we can address anything that crops up in a future PR.