Gametime: Features update

* Added moon phase and moon percent
* Added short day names
* Cleaned up //gt help output.
* Confirmations of changed settings
* Cleaned up alpha-setting text.
* Should now hide on login/logout.

Known Issues
* Sometimes gametime may be a single game minute off. Issues with
rounding.
Changed version

Last changes included, updated version to 0.5.
Merge pull request #349 from thatdudegrim/master

Gametime: Moon phase, other features, cleanup, help-text.