Migrate the various dialog windows into their own classes and files.

[aliciasprig]

The main class flist_messenger remains too monolithic, with one of the causes being that all the logic and data for dialog windows reside there. The fix of course is to move all the dialog windows out into their own classes and files.

• Channel list Improve the channel selection dialog. #68
• Character profile Refactor Quick Profile dialog #70
• Make room
• Friends/bookmarks list
• Global settings
• Channel/PM settings
• Login and character select
• Set status
• Report
• Timeout
• Help

[kythyria]

A minor note: The login and character select aren't technically separate dialogs, a property which I'm retaining. That logic is moving, though, so it'll be its own widget and possibly controller class.

EDIT: The UI parts have moved out of the main class almost entirely as of #77