Consolidation in playTTSFromText()

Removes local variables that are only used once.
Move Windows directory discovery to paths module

With this, the paths module now has a WINDOWS_DIR constant that is set
to None if the Windows directory cannot be located or if the user is not
on a Windows platform.
Enable/disable debugging options

Adds a new "Debugging" tab to the configuration window. This new tab
includes checkboxes that are wired back to the user configuration to
enable or disable the debugging features.
Clean up Qt action bindings

Simplify these to use the direct method, as available.