Refactor metafile-writing to use $MM->stashmeta($text, $file)
Exportable write_file_via_tmp function, put make_type code in MM_Any
Have make_type use inheritance
Use intermediate files to store META.* and *.ppd files
Make t/meta_convert.t data-driven
Merge pull request #187 from mohawk2/metastash

Meta 2/2: stash metadata files in files, not Makefile