bug#51082: [PATCH] erc-prompt: support substitution patterns "%target" and "%network"

[J.P.]

v2. Simplify `format-spec' helper. Demote `erc-fill-wrap-use-pixels' to
normal variable. Simplify option `erc-prompt-format' and make example
value default. Add substitution for showing channel or user mode based
on context. Add tests.

(Also, make myself primary author of last patch to spare others from
unwanted attribution.) Note that a patch from bug#67220 is also now
included because it's become a dependency.

0000-v1-v2.diff
Description: Text Data

0001-5.6-Don-t-associate-type-D-channel-modes-with-args-i.patch
Description: Text Data

0002-5.6-Don-t-inherit-properties-when-refreshing-ERC-s-p.patch
Description: Text Data

0003-5.6-Use-overlay-instead-of-text-prop-to-hide-ERC-s-p.patch
Description: Text Data

0004-5.6-Optionally-align-prompt-to-prefix-in-erc-fill-wr.patch
Description: Text Data

0005-5.6-Optionally-allow-substitution-patterns-in-erc-pr.patch
Description: Text Data