Preferences Fixes (including no restart requirement after Reset All)

Some various fixes to the config and preferences.

* When show mode settings are reset, the config properly gets cleaned (it had previously not been cleaning the entire directory of settings associated with a show mode)
* There was an inconsistency between the ways in which ShowModeStandard settings were saved to and loaded from the config - fixed that up
* There should be no requirement to restart CalChart now after selecting "Reset All".

The problem with Reset All was this:

When the preferences dialogue would reset its values, it would clean up the changes made to the config, but would forget to reset the changes made to the global variables associated with those values. As a result, the old settings were retained in the global settings, and would continue to be used by calchart, even after the config has been changed.