Created by: natefaubion
This fixes the surface-level bug of #217 (closed) by pushing the rhs expr expansion into an invokeed macro, which expands it before it goes into either macros, giving it the correct context for # to work.
I had to change the pattern matcher signatures to take a context instead of just an env so that I could give expr and invoke a complete expander context. Otherwise templateMap was empty, and #{} wouldn't work.