Improve Asset Reloading

- Unloading assemblies needs to be redone so that it actually works properly
(it should be noted that fully unloading assemblies will never be possible using .NET Framework and due to how the game is built)
- Hot-swapping assemblies needs to be done in a way that accounts for dependencies
- Hot-swapping maps and content can cause concurrency issues, and not all assets can be hotswapped reliably