init v2.2.1
mapper
added more methods to Metadata (mostly `dunder`s)
added `parallel` & `vias`
rename method _mapper to mapper
updated CHANGES.txt
updated MANIFEST
updated READMEs (vias)
updated READMEs (vias)
add comment
add comment
updated READMEs (cleanning)
updated PKG-INFO
more sys paths for conf
updated READMEs (dev notes)
better fmt
release 2.2.1