the old mechanism wasted most of the input bytes, and chewed a lot of
CPU, making it impractical to do GPS detection for a GPS attached
after startup
The new code is async, and detects a GPS by looking for a fully formed
packet with the right checksum for each GPS type
this will hopefully fix the NO_GPS problems that have been regularly
happening in recent months. I will watch the logs carefully to see if
the problem recurs
Nuke AP_GPS_IMU, as nothing is using it anymore.
Simplify the handling of no GPS/no fix detection.
Fix prototypes for ::init and ::read.
Update AP_GPS_Auto and corresponding example, nearly ready for primetime.
Use uint8_t rather than byte.
Strip some _error() calls to save space. More could still go.
git-svn-id: https://arducopter.googlecode.com/svn/trunk@1246 f9c3cf11-9bcb-44bc-f272-b75c42450872