disable groupbox if no layer is selected
edit_area:
added layer_moved() signal
added pos x, pos y ui elements
edit_area:
added repaint_request()
adapted to edit_area::repaint_request()
layer:
added set_position_x(...)
added set_position_y(...)
edit_area:
added global_transform
added getter global_translate()
added slots translate_x/y_request(...)
added slots set_translate_x/y(...)
using the global transform
ui:
added new translation changing elements
main_window:
adapted to new global translation
main_window:
added edit_area shortcut
edit_area:
fixed some mousebugs