[MPlayer-dev-eng] Code reorganization & effect on GUIs

[Uoti Urpala]

I've done some reorganization of mplayer.c which moves the
command/property handling to a separate file and to help with that also
creates a context struct to replace lots of different locals/globals.
It's mostly ready but requires a few tweaks such as better names for
some things etc. It's not meant as a final state for the files but as
the changes already touch a lot code (I don't expect anyone to read it
as a patch...) I think it's better to commit a working version before
changing more.

Most of the changes are mechanical and I don't expect it to cause any
major problems, but because of the size of the changes something might
break temporarily, for example there could be missing headers or other
problems for some features that I don't have enabled locally.

Since the gtk and win32 GUIs try to access some globals that were
cleaned up they won't currently compile. I haven't tried to fix them yet
or even check exactly how many changes they'd need (but it should be
possible to at least hack them to work without any complicated changes).
I have a two questions related to the GUIs:
- is anyone else willing to clean up/fix the interface the GUIs have
  towards the MPlayer core?
- what are opinions about letting the GUIs temporarily break while
  cleaning up MPlayer? Further cleanups will likely require more changes
  to the GUIs, but I'd rather not check/fix them every time, and I can't
  even test the win32 GUI.