Support adding current tab's title to the breadcrumb trail

For example while in ../admin/config/regional/language (active tab is "List") the trail is:

Home » Administration » Configuration » Regional and language » Languages

...and when in the "Detection and selection" (../admin/config/regional/language/configure) or "Icons" (../admin/config/regional/language/icons) tabs, the trail is:

Home » Administration » Configuration » Regional and language » Languages » Languages

Now, if the current tab's name was offered as an option to be added to the trail, then it would be:

Home » Administration » Configuration » Regional and language » Languages » Detection and selection

and

Home » Administration » Configuration » Regional and language » Languages » Icons

It does make more sense, doesn't it? Thanx for considering this one ;)