* experimental clean-up / reduction on two of the FG headers:
(I'm going to await feedback on the developers list before doing more of
these, to avoiding going over files multiple times, but in principle it
seems pretty straightforward.)
* final fixes for SG_USING_STD removal
passing it along to FlightGear.) I notice that the serial port read only
seems to work correctly if I read one character at a time. Multicharacter
reads seem very unreliable.
