Automatically add highway=track if tag tracktype=gradeX is added

[flaimo]

There are a lot of complementary tags, that don't make sense without their corresponding main tag. For example if a add an tracktype=gradeX, it only makes sense if there also is a highway=track. similar keys are recycling_type, shelter_type, a.s.o.

It would be a nice time saving feature if, for example, I add a tracktype=gradeX to a way, that the highway=track gets added automatically (as long as there isn't already a highway entry tagged). same goes for the other complementary tags.