Added: New Weather Class Methods and Global functions

Fixed: Add Corpse, RemoveCorpse and ConvertCorpseForPlayer. Also added null checks to the corpse variables. ConvertCorpseForPlayer will now return the corpse too.

- New Weather Global Functions -

* FindWeather(zoneId) - Finds the weather by zoneId and returns the weather

 * AddWeather(zoneId) - Adds weather to the following zone, also returns weather

 * RemoveWeather(zoneId) - Removes weather from a zone

 * SendFineWeatherToPlayer(player) - Sends WEATHER_STATE_FINE weather to the player

- New Weather Methods -

 * GetScriptId() - Returns the weather's scriptId

 * GetZoneId() - Returns the weather's zoneId

 * SetWeather(weatherType, grade) - Sets the weather by weather type and grade

 * Regenerate() - Calculates weather, returns true if the weather changed

 * UpdateWeather() - Updates the weather in a zone that has players in it, returns false if players aren't found

 * SendWeatherUpdateToPlayer(player) - Sends weather update to the player

EmuDevs thread regarding this update: http://emudevs.com/showthread.php/1961-Eluna-Added-Weather-functions-and-methods?p=12780#post12780