We added a `.dir-locals.el` in commit: 9a77017d87
There's no need to have it per-file, with that people might think
to add other editors, which is the wrong direction.
Closes: #1206
Approved by: jlebon
Don't expose GChecksum in APIs. Add a new stream class which allows
us to pass an input stream somewhere, but gather a checksum as it's
read.
Move some bits of the internals towards binary csums.