Namespace separation, SM1.12 support, no hacky initialization

[Alienmario]

This is a larger edit to get the include to work with SM1.12. I've also made changes along the way to reduce namespace conflicts for larger plugins by adding a prefix, using static variables, or moving methods to methodmaps. I've also removed the OnPluginStart redefine and moved auto-initialization to StudioHdr constructor.

Basic usage with model_path constructor remains the same as before. GetEntityStudioHdr becomes StudioHdr.FromEntity.