Rework chats list
Code cleanup

Everybody loves code cleanups! CLEANUPS CLEANUPS CLEANUPS CLEANUPS.

And headers. Headers are so awesome. OMG.

Replaced MySettings.cpp and SettingsDBWrapper with one class which does
exactly the same but in more... logical way. Removed stuff from
MessageWrapper which shouldn't be there, I think I could remove it as
soon as I find a way to do exactly the same in JavaScript. Merged
AccountsListModel.h and AccountsListModel.cpp cause who needs cpp file
if you can do all this in header?