this will require more temporaries, but is probably less magical.
also, it means that borrowck matches trans better, so fewer crashes.
bonus.
Finally, stop warning about implicit copies when we are actually borrowing.
Also, one test (vec-res-add) stopped failing due to #2587, and hence I
added an xfail-test.
Fixes#3217, #2977, #3067
This involved adding 'copy' to more generics than I hoped, but an
experiment with making it implicit showed that that way lies madness --
unless enforced, you will not remember to mark functions that don't
copy as not requiring copyable kind.
Issue #1177
This goes before a snapshot, so that subsequenct patches can make the
transition without breaking the build. Disables kind checking pass, makes
parser accept both new and old-style kind annotation.
Issue #1177
