-plot projections on a new specific GUI view_field, to avoid the multiplication of active figures
-introduce a ruler in uvmat (in menu/Tools), to measure distances and angles
-insert automatic detection of points for geometric calibration: tool 'detect_grid'. Four points, deliminating the grid to determine, must be marked with the mouse, as well as the physical grid. Then the points inside are automatically detected.
-reading plane positions in ImaDoc? improved to deal with volume scans
