auto-update "Updated" dates from in-list values

[DandelionSprout]

Many filterlists have info tags inside them á la ! Last updated:, ! Last modified:, ! Updated:, # Updated, # Generated on, # TimeUpdated:, ! TimeUpdated:, and so on. And those dates are almost always pretty accurate indicators for when a list was last updated. Therefore I propose that the Updated values on FilterLists.com could be auto-updated with such values whenever they are available.

There are admittedly a lot of date formats that'd need to be accounted for, e.g. 05 Sep 2018 (…), 05September2018(…), September 5, 2018, 2018-09-05 (…), and probably some other ones as well.

Edit: I also propose that lists whose such values are more than 730 days (2 non-leap years) ago could've had those dates auto-added to the "Discontinued" values as well, but that'd be merely a secondary bonus.

[collinbarrett]

closing as duplicate of #202

Capturing these dates is certainly on the roadmap. I am unsure whether we will use them as the primary source of the last updated date, however. I have found that some lists auto-update their date on a schedule even if the list hasn't actually changed at all.

However, in the latest changes to SnapshotService, I am determining if a list has been updated by its md5 hash, which will be different even if only the date metadata has changed. So, I guess that isn't as relevant anymore.

[collinbarrett]

opened #440 to capture your edit

[collinbarrett]

Fyi, on your last "Edit:", see: #440 (comment)