2.15.6 (unstable)

Gio:
* Removed most vfuncs, because they are not useful to application developers, 
  and are a likely source of errors. (Murray Cumming)
* DesktopAppInfo:
  - Added Added create(), create_from_file(),
    is_hidden() and set_desktop_env()
    Renamed new_from_file() to create_from_file().
    (José Alburquerque)
* File: equal(), get_relative_file(), contains_file(): Take const File 
  parameters.
* FileAttributeInfoList: Added dup().
* MemoryInputStream: Added add_data(const void* data, gssize len).
* Mount: Really added signals.
* MountOperation: Wrapped the ask-question signal.
  (Murray Cumming)
* Volume:
  - Added should_automount().
    (Marko Anastasov)
  - Really added signals.
    (Murray Cumming)
* UnixOutputStream, DataOutputStream, DataInputStream: Made constructors 
  protected.
  (Marko Anastasov)


Documentation:
* Install a devhelp file like the existing gtkmm one.
  (Jonathon Jongsma)