[simpits-tech] MFD shared memory support

[Erwin Neyt]

MFD data extraction is a fact. Don't ask me when it will be available,
that's up to G2I. But they are really exited, so there is a good chance they
will include it in a future release.

G2I will also welcome my bugfixes for sh.mem. code.

bugs found so far:

- Fuel qnty values not updated if gauge not drawn on screen
- Gear handle light value not updated if not drawn

If you know of any other bugs, please let me know!

Erwin.