Add compat to ERC

[J.P.]

Hi Philip,

Thanks for making compat! Although most of it's way over my head, the
parts I did manage to grasp look really well done. It seems to work
great with ERC on Emacs 27 and 28, so much so that I'd like to make us
the first :core package to require it, if that's acceptable to everyone.

I've attempted a patch but had no real clue what I was doing. Please
tell us what needs changing, assuming it's salvageable; otherwise, feel
free to take over or, if you'd be willing, provide a replacement
whenever time allows.

TIA,
J.P.

0001-Add-compat-from-GNU-ELPA-as-a-soft-dependency-in-ERC.patch
Description: Text Data