Changing a filter should only affect the view is it used in

[janwilmans]

Changing a filter should be applied only to the view (taking into account the offset of the view), so if +2M lines are in the buffer but only very few lines in the view, a re-apply should be really fast.

[janwilmans]

Tested: seems to work normally, maybe already fixed? Keeping it open for more testing