gitignore update
many "Qed" ==> "Defined" for computing Proves_dec

I may have made too many of the “Qed” definitions “Defined”, I can
change some back if needed.

The difference is that the internals of “Qed” definitions are opaque,
and “Defined” are transparent. That’s why compute can now decide
provability of properties, whereas before it seemingly spun forever.