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.
GlideComputerAirData: forward-declaration cleanup
Merge branch 'master' of git://github.com/hjr/XCSoar
AirspacePredicateAircraftInside: inline the constructor
AirspaceSorter: remove unused class AirspaceFilterPredicate
AirspacePredicateHeightRangeExcludeTwo: move code to OutsideAirspacePredicate
AirspacePredicateHeightRange: don't derive from AirspacePredicate

Make this a simple function object.
AirspacePredicate: add utility template WrapAirspacePredicate
ProtectedAirspaceWarningManager: apply naming convention
Airspaces: fix coding style
Makefile: add OutsideAirspacePredicate.cpp to libairspace.a
Airspaces: make "owns_children" const
Airspaces: copy master metadata in SynchroniseInRange()

Eliminate the "master" constructor.
RoutePlannerGlue: include cleanup
Airspaces: use KDTree::visit_within_range() instead of find...()

Eliminate temporary vectors.
OLCTriangle: use empty() instead of size()==0
OLCTriangle: move the std::vector allocation out of the loop

Reduce number of malloc() / free() calls by reusing the old
std::vector area.
OLCTriangle: use range-based for