change form_gui_data structure to prepare for groups
group code (not tested)
glue code for masks group
add edit button inside the iop
correct bugs in groups
fix some bug in group selection/edition
new design in iop with simili bauhaus comobox
implement add circle/curve
enhance group drawing/selecting/moving
implement "dont use masks"
implement add existing shape
update correctly iop masks line
disabled don't use masks if no masks in use
basic treeview to for mask manager
base for context-menu in treeview (manager)
restrict selection
manager : add values to tree rows
masks : allow mouse control if module is NULL
manager : implement add circle/curve
manager : implement selection change
manager : synchronyse selection
manager : implement shape remove/delete
manager : implement grouping (not complete)