NEWS: prepare for 6.7.7
CirclingComputer: check if turn_rate_delta_time is defined

And initialize on first call when possible. Fixes a uninitialized
use of last_track.
Terrain/RasterWeatherCache: add method IsTerrain()
Terrain/RasterWeatherCache: add method GetMapName()
WeatherTerrainRenderer: use map name to look up color ramp

Don't use hard-coded index numbers.
GlueMapWindow: update RasterWeatherCache as early as possible
RasterWeatherStore: store per-map info in an array

Show only the maps that are really present in the ZIP file and
remember the times available for each of them.
Terrain/WeatherTerrainRenderer: make the ColorRamp array static+constexpr
Terrain/WeatherTerrainRenderer: add fallback to LookupWeatherTerrainStyle()
Terrain/RasterWeatherStore: scan all files from the ZIP
UISettings: split new struct FormatSettings from this struct
UIGlobals: use nullptr instead of NULL
UIGlobals: expose FormatSettings

Expose the FormatSettings structure to allow access by the lower
layers of software to user settings
Use new UIGlobals for dlgWaypointEditShowModal

Switch to the lighter-weight and global API to access the coordinate
format selected by the user
GeoPointDataField: make format const
GeoPointDataField: add method GetFormat()
Form/DigitEntry: Extend editing of waypoints to all lat-long formats

UTM yet to be supported
manual: Fix typo in thermal assistant chapter

Fixes trac issue #3430
Merge branch 'v6.7.x'
Correct UTM todo comment

Some comments incorrectly referred to UTC and not UTM format