The reflection-based importer, for file types that aren't imported via a
legacy bkm file, dynamically searches the current module (i.e.
BizHawk.Client.Common) for all IMovieImport instances with the
ImportExtension attribute.
This is difficult to truly test without more non-legacy import
implementations, but appears to work with a dummy .pjm file.
It may be desirable to instead search the current assembly instead of
the current module, but I think all implementations should probably go
in BizHawk.Client.Common, so I chose to search by module instead.
adelikat