Add support for Windows

[Nick Miyake]

At a high level, this would require:

• Provide a replacement/alternative for invocation script besides godelw (godel.bat or similar)
• Audit for any places where / is assumed as path separator and use path.Join or equivalent
• Publish Windows binaries for gödel and all plugins and release them
• Ensure that plugin/asset invocation handles adding .exe on Windows