swap coordinates and filters

[zsiki]

New function to swap coordinates, for example swap east and elevation. It is necessary if a calculation should be done not in the east-north plane (e.g. area and perimeter).
Side effect (danger) after the swap of coordinates the observations are useless. So a new data set should be created (like save as) without observations.

[zsiki]

A more complex Export function would be implemented where point filtering (by point id, code, rectangle) and coordinate swapping are available. A FilterParams dialog has been started some times ago in loadgeo.tcl, but not finished.

[zsiki]

Swap coordinates has been added to the Command menu of the coordinate list window.