Feature #1173: Saved Game: include weather state

Removed some unused state in and changed Ogre::String to std::string in
WeatherManager.
Move weather state save/load to a new class
Fixed header include guard to match filename
Fixed include to use C99 header, not C++11 header
include local variable state in saved games
fix for previous commit
Fix typos
Refactored settings window
Just some notes for future maintenance.
Merge remote-tracking branch 'slothlife/weather_save'
some ambient light cleanup
added lighting switching
updated credits file
added day lighting mode
added night lighting mode
added bright lighting mode
Play deathknockout/deathknockdown animations when appropriate
ToggleAI: Report current status on toggle
Fixes #1224: Store class name instead of id in savegame header
Savegame dialog: use locale-aware datetime format