Add mechanic to reset InxParameter in Extensions

This allows to use the attribute "reset_to_default" in parameters in inx-files for extensions.

implements it for book, float, int, path and string.

To use: example in jessyink_effects.inx: < param name="effectInOrder" type="int" min="1" max="100" gui-text="Order1:" reset-to-default="true" >1< /param>

closes #3934 (moved)