vertical and horizontal speed are not configurable with other units

[speed-axel]

The user should be able to select different vertical and horizontal speed units in the configuration of KFLog. Furthermore all unit related values (distance, altitude, speed) should be displayed in the user's selected unit.

[speed-axel]

Class Speed taken over from Cumulus and integrated into the configuration unit window. A user can define now different horizontal and vertical speed units.

The statusbar of the main window shows now the values in the user's selected units.

Other widgets must be adapted to that new possibilities.

[speed-axel]

The DataView window considers now the user's set units. If the units are changed by the user the DataView window will be refreshed now.

[speed-axel]

The MapControl height and width values are displayed in the user's selected distance unit now.

[speed-axel]

done