cylc list prints just tasks or namespaces, correctly.

Dumped the pseudo-tree print code. Closes #335.
Updated user guide for "cylc list" changes.
Add task-only single-parent tree print to "cylc list"
Fixed typos in list command help.
Detect terminal local in LANG
Tidied the db print command code a bit for clarity (null effect).
Namespace titles with padding for "cylc list".
Merge branch 'db-print-tidy' into 335-cylc-list-overhaul
Merge pull request #336 from hjoliver/335-cylc-list-overhaul

335 cylc list overhaul