DebugReplay: move NLineReader out of DebugReader class

Prepare creating a DebugReplay from a std::vector.
IGCFix: Apply() copies extentions, too
DebugReplayVector: implement replay from memory

This class shall be used for replays directly from memory, for example
for replays from a database (like the live tracking data) or if someone
wants to reduce file-IO for some reason.
python: initial python module commit

This python module does nothing more than reading a IGC file and
storing it in memory if desired.
python: add FlightPath functionality...

... but without path reduction yet.
python: add small test script
build/python: add build instructions for xcsoar python library
python: add takeoff/release/landing detection method
DebugReplay: add detail level

Each fix should have a detail level at which it will be shown on
a map. This is only useful for skylines atm.
Flight: make flight reading code it's own method
IGCFixEnhanced: add clock
python: implement polyline reduction code
DouglasPeuckerMod: add hard limit for number of points
PythonGlue: fix start and endtime of polyline reduction
python: implement flight analysis
python: implement google polyline encoding
python: clean up
PythonGlue: add encode method to flight object

The fast lane to create a encoded flight dictionary
PythonGlue: obey python error handling
GoogleEncode: delta-encoding is optional