remove `gp` alias
indent a few less-significant gcd print statements
skip redundant first git-untracked-files removal
hooks for preserving certain git-untracked files

specify patterns to preserve either via a file or an env var.
some spacing and clarity tweaks
default GIT_COPY_DIFFS_PRESERVE_UNTRACKED value
factor out some remote-parsing regexs
use ‘user’@ when copying diffs to remotes
support mirror-pushing to local “remote”s
wrap the “remote” regex match object in a class
add `git diff HEAD` alias