app/core/Pickle.lua: replace outputs by copying to the old medium; tidy.
app/core/Pickle.lua: replace outputs by copying to the old medium; tidy.

app/core/Pickle.lua:
	output(): only map to source/destination when non-empty & non-generated;
	output(): only call replace() for same-type mediums.

komiga/pickle,komiga/pickle,komiga/pickle,komiga/pickle