Take care of ordering of subcommands

[neithernut]

The ordering of subcommands should be consistent between

• src/cli.yaml
• the implementations in src/main.rs
• the match in the main() function in src/main.rs

The porcelain commands should be separated from the plumbing commands, e.g. plumbing first, then porcelain.

Should be done before any of #37, #38, #41, #50, #51, #52 and #53, IMO