History Function with AT Parameter

New history function to see how a wiki looked at a certain time. The difference between REV and AT Parameter are:

• all datetimes are allowed (>page creation time)
• it also changes the internal mediafiles to the given datetime
• all internal links are modified so you can navigate through the wiki without losing the timeinfo

add parameter at=<datetime> to the wiki url.

See Unix_time

https://www.dokuwiki.org/date_at?at=1412020375

see strtotime

https://www.dokuwiki.org/date_at?at=2014-09-29 21:54
https://www.dokuwiki.org/date_at?at=-1 week

• All information related to the metadata.