Builtin commands are now gathered more tightly in a single module,
Hledger.Cli.Commands, reducing duplication and facilitating change.
The tests command was difficult and has been dropped for now.
The obsolete convert/info/man commands have been dropped.
cli: refactor: a proper commands list, better Main/Commands separation
The legacy "convert" command has been dropped.
The activity command's module is now named consistently.
