Initial commit for discussion

A lot of this is still stub code, but far enough along for discussion
and feedback. Some good example tests are TestVibration and TestBrownout

datatypes handled correctly now (previsouly all read as floats), added
flag to skip bad input lines, now prints some general log info (size,
duration, etc), added some basic performance timing,
added PM slow loop check, first version of xml output
minor
adding Roberts bad PM performance log
minor
changed command flags a little, tidy, started on TestPitchRollCoupling
minor
added test for dupe log data
minor
fixed plane+rover parsing, added test for underpowered copters
minor
added BETA feedback info to output
minor
added unit test, started moving from dictData to listData

added unit test, started moving from dictData to listData, cancelled
pre-3.0 log reading, separated DataflashLog constructor and read() call
minor
added GPS glitch detection to GPS test
minor
report skippedLines, cleaned up DataflashLog.read() error handling
combined statusMessage and extraFeedback
added LogIterator, copter roll/pitch > max lean angle test,