Add ability to have custom meta tags for each download category about metatag

[lonalore]

I had no time to deal with it since Sunday, I hope I can continue working on this tonight.

[Jimmi08]

Great. Until now nobody was able to say how to replace missing e_PAGE constant. If your solution is general and correct, we could tell this to CaMeRon. There are plans to make this constant back but it seems as not needed now. I will check your solution asap, I am on mobile now. Gallery plugin has the same problem. Thanks for this.

[Jimmi08]

Oh, I had problem with missing events with download categories and not event names in admin area. I am not able now to check all your code if you fixed this too. This plugin is awesome.

[mostym]

@lonalore Does this allow me to define meta tags for each individual download category? I have about 40 download categories and each one needs to have it's own meta tags. I must have installed this incorrectly.

Thanks!

[Jimmi08]

Great. Until now nobody was able to say how to replace missing e_PAGE constant. Thanks for this.

Ok, this is the solution for download plugin. With gallery plugin e_CURRENT_PLUGIN is not defined.

[lonalore]

There is a pending pull-request for this issue: e107inc/e107#3787