Options: gather as much data from config file first
Options: further command registry fixes

This updates the documentation for some of the recent changes to
subcommand handling, and ensures that the server core is shut down by
bcfg2-info.
Options: Fixed non-path database name parsing

The database name is sometimes a path (SQLite) and sometimes not
(MySQL, PostgreSQL). This introduces a new Option type,
RepositoryMacroOption, that expands <repository> macros without
canonicalizing the path, so SQLite users can use <repository> in their
settings but MySQL users' database name settings will not be destroyed
by path canonicalization.

The unfortunate downside is that SQLite users can't use ~ in their
database name.