Tardis:Ogg format banned

As explained at Thread:144139, Mac OS X's version of Safari lost the ability to show any .ogg files at the introduction of Mavericks in 2014. As far as we can determine, iOS never had this ability. Since our site statistics show that we have a relatively high number of OS X and iOS users, and until the underlying software can be updated, .ogg files will always remain inaccessible to a healthy chunk of our users.

Therefore, in the interests of reaching the widest possible audience, the .ogg format is banned on Tardis.
 * ''Note that you will still find some .ogg files at Tardis which were uploaded before .ogg handling broke for Apple products in 2014. Their presence doesn't obviate this rule, and uploading new .oggs is a blockable offence.