Items are either dragged by their origin or moved by a vector (depending on the number of selected items) (GAL).

3d viewer: Add high quality mode option is realistic mode (Shows holes in copper zones, but with longer calculation time)
Gal: fix a very minor issue: the keys to switch between copper layers are now - and + (according to the doc and the normall mode), instead of - and =

Outline mode can be set up on any layer.

Introduced SELECTION_CONDITIONS to determine which menu entries should be visible in the SELECTION_TOOL context menu, depending on the selection.