Merge two Ovale settings that had identical meanings.

"/ovale show|hide" now toggles the "Enabled" state of the Ovale icon bar.
Factor out the debugging and trace code into an OvaleDebug module.
Register debug options with OvaleDebug module.
Sort default options alphabetically by group.
Change frame positioning to be offsets relative to screen's center.

Add two controls on the layout settings to set the horizontal and vertical
offsets from the center.  This makes Ovale's frame positiioning more
consistent when changing screen resolutions or screen sizes.

This change unfortunately resets the position of the Ovale icon frame for
everyone.
Make the version string nicer if using a development version of Ovale.
Move OvaleOptions slash commands into their related modules.
Remove spurious brackets from the README file.