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
Fixes #1209: Tarhiel never falls

There are a few pitfalls with this code:
 - Gravity is only considered when applying queued movement. Therefore, make sure to queue some movement every frame. (Could be refactored in the future?)
 - The character controller never detects being in free fall (!World::isOnGround) unless movement has been applied.
Fix build error
Merge remote-tracking branch 'scrawl/master'
include local variable state in saved games
fix for previous commit
Just some notes for future maintenance.
Merge remote-tracking branch 'slothlife/weather_save'