Macropy

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- Error messages are now raised at run-time rather than at import time, with other improvements (double stack traces, catchability).
- `enum` macro now has much better error messages
- Improved error messages for mis-use of stub functions outside their related macro (e.g. the `u`, `name`, `ast` stubs for the `q`/`hq` macros)
- Improved error messages for invalid case class signatures
- Hygienic Quasiquotes now allow lexical capture of module objects

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- Removed unit test from PyPI distribution

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- Fixed a bug in `ast_ctx_fixer`
- `gen_sym()` is now `gen_sym(name="sym")`, allowing you to override the base name
- Implemented `macropy.case_classes.enum` macro
- Implemented `macropy.quick_lambda.lazy` and `macropy.quick_lambda.interned` macros