[BUG] Crash when cancelling out of the password prompt #446

Cancelling out of the password prompt using Ctrl-C or Ctrl-G causes ncmpcpp to crash with the following error:

terminate called after throwing an instance of 'NC::PromptAborted'
  what():  

This is because the exception in question is only caught in the first section of the main loop, and not when handling MPD::ServerError, which is where the password is read.