Fix pushing the topic name of a new change

Signed-off-by: Gustavo L. de M. Chaves <gnustavo@cpan.org>
Accept multi-valued variables in the configuration

Inspired by the Git::Hooks module implementation, I made the %Config
hash map variable names to array-refs of values. This way it is
possible to have more than one value associated with a variable and
use the list of all values when it makes sense, or just the last one.

Signed-off-by: Gustavo L. de M. Chaves <gnustavo@cpan.org>
Make 'query' accept named queries

The name of a query is shown instead of its expression in the output.
The 'list' command takes advantage of this to show output more similar
to the 'my changes' Gerrit page.

Signed-off-by: Gustavo L. de M. Chaves <gnustavo@cpan.org>
Show name and expression in 'query' headings

Signed-off-by: Gustavo L. de M. Chaves <gnustavo@cpan.org>
Substitute 'my' for 'list' command

The previous 'list' command behaviour is now performed by 'my
changes'. But 'my' supports other change specifications, viz. 'my
drafts', 'my watched', and 'my starred'. It's inspired by the 'My' tab
in Gerrit's web interface.

Signed-off-by: Gustavo L. de M. Chaves <gnustavo@cpan.org>