Improvement: Add support for .NET libraries

[milnet92]

I'm working on adding support for .NET library references. It's under construction in features/net_assemblies branch.

As of now, It's mature enough for the interpreter to interpret itself 🏃

[milnet92]

Current limitations:

• ❌ Generic types cannot be used in declarations
• ❌ using keyword is not supported so types from .net references must be used with full type name (i.e. namespace.type form)
• ✅ Optional parameters must be always passed
• ❌ Methods with multiple declarations can be used, but the editor will show always the first declaration