clean-uri was deleting fragments and queries
registry was dropping locks
probably something else I'm too lazy to look back at what changed

Very hacky right now, only has shell and init subcommands, but shell
actually runs a shell with supplied packages.

Sub-aset separator is ":" instead of the nix standard ".", need to
consider options.

better try to color on a terminal only, don't write color codes if output port is a file. still does not do a great job

Breaks existing spurs that don't ship a spur-locks.scm

Adds url field and allows for a much easier interface to spurs
Only URLs supported right now are git+https and https (with implicit git)
No registry