contrib: check reference to old selenic.com domain
Now, all URL in Mercurial source tree should refer mercurial-scm.org
domain instead of selenic.com.
*.po files are ignored in this patch, because they might contain
msgid/msgstr coming from old source files.
This ignorance seems safe enough, because such msgstr should be
ignored at runtime, because:
- msgid corresponded to it should be invalid, or
- msgstr itself should be marked as fuzzy at synchronized to recent hg.pot
If any additional examination for *.po files is needed in the future,
let i18n/check-translation.py achieve such examination.
BTW, some binary files (e.g. *.png) are meaningless for checking
reference to old domain in this patch, but aren't ignored like as *.po
files, because excluding multiple suffixes is difficult for regexp
matching.
(binary:application/octet-stream)