Highlights:

  - FrameContainers are now generic, according to their window type
  - Writable frame containers now handle their tab completers
  - Redirect plugin works again
  - Windows are no longer actively requested from the UI; the UI
    creates and adds them in response to events from the WindowManager

fixes issue 3997, fixes issue 4000, fixes issue 4012, fixes issue 4030
fixes issue 4027, fixes issue 4028, fixes issue 4029, fixes issue 4031
fixes issue 4032, fixes issue 4033

Change-Id: Ife307728e46bd3b6dcd189be6886ab8b6fbd9212
Reviewed-on: http://gerrit.dmdirc.com/1144
Reviewed-by: Gregory Holmes <greg@dmdirc.com>
Automatic-Compile: Gregory Holmes <greg@dmdirc.com>