WeatherRegistry soft-dependency integration

[AndreyMrovol]

This PR aims to add soft-dependency integration with WeatherRegistry (a weather controlling mod) by changing the references from vanilla's LevelWeatherType enum to WeatherRegistry's WeatherManager ones, as well as to:

• Remove Imperium's hardcoded weather names (correlated with enum values) to allow for modded weathers usage
• Create an WeatherData util class to allow for getting game's weather data from WeatherRegistry as well as the Enum (old/vanilla method)
• Add a reference to WeatherRegistry's WeatherController for changes done via Imperium's UI to be applied correctly

I've also included the dropdown value fix you've mentioned and added an enum value resolver as per my message - the +1 fix.

Tested both with and without Registry - works without any issues.

[giosuel]

Manually merged in 1183f00b05eb0646c27bee7e100343d85a93c111