Package marquise.h, load that on import rather than relying on a symlink

Previously, installed versions of pymarquise broke on import due to
reliance on a hardcoded symlink in the repo directory. As pymarquise
will need to track libmarquise versioning in any case, this is
preferable.
Merge pull request #7 from anchor/fix-install

Package marquise.h, load that on import rather than relying on a symlink