Manual en flash: Added promo for manual, toc,
 formatting tweaks for both screen and print.
Logger/ExternalLogger: Create "logs" directory automatically

This caused failures for users who never used XCSoars internal loggers
before trying a flight download from an external logger.
Merge branch 'v6.7.x' of git://github.com/hjr/XCSoar into v6.7.x
po: update German translation
po: update Ukrainian translation
po: update Spanish translation
po: update Ukrainian translation
po: update Ukrainian translation
Input/InputEventsTask: "next" is used as the event data to switch to next TP

Fixes trac issue #3270.
Manual avionics & airframe: Fixed wrong ref. to device config.
Util/StringUtil: Add StringStartsWithIgnoreCase function
Airspace/AirspaceParser: Relax parsing of TNP airspace files

Fixes trac issue #3272.
Merge remote-tracking branches 'hjr/v6.7.x' and 'apf/v6.7.x' into v6.7.x
Math/Point2D, GDI/Point: add operator-
OpenGL/Triangulate: use operator-
OpenGL/Triangulate: use "auto"
TopographyFile: move code to LoadShape()
TopographyFile: use "zzip_dir" without "struct"
TopographyFile: make a few attributes "const"
TopographyFile: don't use NonCopyable