Added option to adjust pressure to diveO2 reference: The DiveO2 internal pressure sensor is more prezise (on surface) than the pressure sensor of the OSTC which is focusing on measurement of pressure under water (different scale). The offset of the OSTC sensor may now be compensated using the maintainance menu. During the implementation the menu has been restructured. Befor it was based on the confirmation dialog, in the new version it is a stand alone menu.