Tweaks to handle Stellarium's Meade LX200 mode.

Tested using Stellarium 0.12.4 under Mac OS X, configured using
a virtual COM port /dev/ttyp0 mapped to the Raspberry Pi TCP/IP
port using:

./socat GOPEN:/dev/ptyp0,ignoreeof TCP:raspberrypi:4030

Tested with socat-2.0.0-b6.tar.gz with xio-ip6.c edited to add
include line "#define __APPLE_USE_RFC_2292" to the start.
Hack for Stellarium's version of the Meade LX200 Sr and Sd commands

It appears Stellarium inserts extra spaces in these commands, and
instead of "*" tries to use chr(223) as the degree symbol.
See https://bugs.launchpad.net/stellarium/+bug/1272960

Stellarium (at least via socat) seems to break its command at odd
places, and we don't always see the closing "#" immediately...
Can cope with this but it breaks complex NexStar commands like "r"
for goto (which we can't support yet anyway).