Fix bug #1165

As I understand it the pagination code is stripping the extension from the TAG_SAVE_AS , CATEGORY_SAVE_AS , and AUTHOR_SAVE_AS settings. Then an extension is reapplied from the pagination SAVE_AS setting. This means that the TAG_SAVE_AS , CATEGORY_SAVE_AS , and AUTHOR_SAVE_AS settings have no affect on the files extension.

This fix saves the extension from incoming files to be written, strips any extension applied by the pagination code, and reapplies the old extension.

This means that setting an extension the pagination SAVE_AS setting now has no affect, but the other settings have control of the extension.

Perhaps I need to update the documentation?