rose slv: new CLI. Support view and update modes.

In update mode, arguments can now be a `*` (for all task jobs), a cycle
time or a task ID.

Support a `--tidy-remote` option to remove job logs on remote hosts
after their retrieval.

Support a `--archive` option (and removed
`--log-archive-threshold=CYCLE`) to switch on archive mode on the
specified cycle times in the argument list.

Switch off view mode by default in update mode, but can be turned on
explicitly with `--view`.

Some internal logic improvements.
rose suite-hook and slv: logic fixes.
rose slv: plug more gaps for getting task job hosts.
rose slv: minor fix to comments and interfaces.
Merge branch 'master' into rose-slv-syntax
rose slv: handle negative year.
rose suite-log: replace `rose suite-log-view`.
Update CHANGES.md
rose suite-log: --timeout=DELAY option.

Allow the lock timeout to be specified in an option. Reduced to the
default to 300.0s.
Merge pull request #739 from matthewrmshin/rose-slv-syntax

rose slv: CLI rejig

Closes #730