ValExtLinks: Added audit feature which tells the user if there are items in the exception list which are no longer present on the wiki or no longer return the given error code.

ValExtLinks: The messages about skipping URLs now show the wiki page's namespace. Added 504 to known response codes.

ValExtLinks: Changed --suggest-snapshots to --suggest-snapshots-ng and added --suggest-snapshots-ok for getting snapshot URLs for all good links. This can be used to confirm that sites are backed up in case they die in the future, but note that this argument will take hours to run due to the API rate limit. Added awareness of API rate limit so Archive.org will not start blocking script.

Committing sample files to go along with last committed version of ValExtLinks.

ValExtLinks now reads its exceptions list from a wiki page instead of a text file that only I can change.

Val now counts redirects from youtu.be to youtube.com as OK links.  These links will be reported on if the argument --show-yt-redirects is used.  Renamed --show-https-upgrade to --show-https-upgrades for consistency.  Also sorted the file and page suffix arrays and added some more items to them.  Now handling status codes 400, 418, 502 and 530.  Fixed incorrect nbsps in HTML report.  Val is no longer confused by URLs ending in '(' or ')', or which contain a '%' towards the end.

Val now removes the annoying ':80' in many Archive links.

Val now links to wiki pages using HTTPS instead of HTTP. Fixed code that exempts minor forms of redirects from being listed. New arguments --show-added-slashes and --show-https-upgrade allow one to turn off these exemptions. Reworked summary section extensively to be more readable.

Fixed ValExtLinks' reading of Archive API replies. Fix for reading links that happen to have a shebang in them. Now knows how to handle NULL namespace links. Now prints elapsed time.

ValExtLinks improvements:
- Now advises reader of external internal links.
- The exceptions file now allows finer-grained exemption of a URL by matching to the specific page that contains it instead of exempting all occurrences of that URL (but the '*' wildcard will match all containing pages). Currently you can only list a URL once, however.
- The exceptions file now allows external internal and potential intrawiki links to be exempted from the report.
- The path to Google Chrome (for taking screenshots) is now external to the script, supplied as an argument after "--take-screenshots".
- All of OniGalore's interwiki shortcuts are now recognized.
- Protection against failed retrieval of redirect URL.
- Better recognition of unimportant redirects (http->https, added ending slash).