Done, thanks. I made the less common a synonym of the more common in each case (symbolic-link ← symlink, mail ← email, version-control ← vcs); the first was actually proposed ages ago by xeno before he was a mod, but it had no votes, so I just approved it
I also merged them all, so the synonym tags shouldn't exist anymore:
updating post history, 2 rows affected
updating posts, 2 rows affected
updating PostTags associations, 2 rows affected
removing/renaming old tag, 1 rows affected
updating count for master tag, 1 rows affected
merge of [symbolic-link] and [symlink] complete!
updating post history, 8 rows affected
updating posts, 4 rows affected
updating PostTags associations, 4 rows affected
removing/renaming old tag, 1 rows affected
updating count for master tag, 1 rows affected
merge of [mail] and [email] complete!
updating post history, 1 rows affected
updating posts, 1 rows affected
updating PostTags associations, 1 rows affected
removing/renaming old tag, 1 rows affected
updating count for master tag, 1 rows affected
merge of [version-control] and [vcs] complete!