NEWS.txt: add missing line
Android: work around spurious rebuilds

Workaround for Android SDK bug.  Don't recompile if nothing has
changed.
Android: invoke unregisterReceiver()

Fixes callback leak (and warning in logcat).
NEWS: prepare for 6.6.2
OrderedTask: move code to PropagateOrderedTaskBehaviour()
OrderedTask: propagate OTBehaviour changes in SetFactory()

Be sure to update all settings after task type change.
test/TestDriver: check for decimal places in time stamp
VL Driver: IGC Download add fclose()

fclose() was missing.
VL-Driver conv_dir(): replace tm by BrokenDateTime

The function mktime() related to data type tm fails to normalize
time on TARGET PPC2003.
It is replaced by BrokenDateTime, which also makes the code more
readable.
The previously necessary (to meet tm spec) adjustment -1 for month
no longer needed.
The year now needs to be corrected by + 1900 to meet BrokenDateTime
spec.
VL Driver convert_gcs: Replace tm by BrokenDateTime

Description see similar patch for conv_dir()
NEWS.txt: mention Volkslogger fix
doc/manual/dev: single-line comments rule
doc/manual/dev: rules for static, virtual, override, final
AirspaceXSRenderer: Also render "unknown" airspace types

Fixes the display issue of trac ticket #2884.
Manual de: Bulk import of a more recent german manual translation.
manual.mk: Added Claus's beloved index in make rules.
Manual de/ch05_glide_computer.tex: Correct png file name.
Manual images: High resolution topo image.
Manual images: Recent airspace screenshot.
Manual images: Deleted no more used screenshot.