Support partial classes

Partial classes need to be correctly rewritten.

Possibly best approach is to pull all partial classes files into single and compile.

[ ] reach back to tommox86 from forum thread

Start by tracing the existing partial-class rewriting and compilation flow, then review the referenced forum thread for context. Done means partial classes are combined or otherwise handled correctly and the resulting code compiles without breaking the hot-reload workflow.

索引モデルが issue の本文から書いたものです。