Improve macro file compilng

[Olical]

See #46 (comment) for more thoughts.

Right now if you write a macro file the whole project is recompiled. That should still be an option but we should also have a mode where we filter for files that mention this macro file by module name. It's so simple it's silly, but hopefully good enough for almost all cases.

Then if we have a chain of macro files depending on each other we'll need to recursively walk up until we find the real .fnl source files that depend on this macro dependency tree. We would also then need to be really careful not to introduce infinite cycles so we'd have to keep a table of "seen" files in order to not go around and around.

This could allow us (in most cases) to only compile the exact files required. Sometimes we would compile one or two others that mention the module in a comment but that's no big deal. Even if it cuts the compiling workload by 50%, that's a big win on large projects like Conjure!