such as snow level, dust, wetness, and texture set.
Also add a parameter to control whether the snow level moves with METAR,
and retire /environment/mysnow-level-m.
- use just a single "Weather" menu item
- add buttons to switch between global and local weather dialogs
- Rename Global Weather to Basic Weather
- Rename Local Weather to Advanced Weather
fixes for a couple of issues, some improved textures/cloud model changes,
smooth instead of hard visibility transitions, updated documentation.
Also removed 'Test' entries from the menu.
(ThorstenB: Also cleaned-up Docs/ folder, moving local weather
documentation images to sub folder).
