Feature Request: Add support for drops only from naturally ocurring or player-placed blocks

[flareglare]

Is your feature request related to a problem? Please describe. Idea: Have a custom drop only from a block that was naturally existent in the world such as tree logs. Configuration proceeds as with any other block and drop.

I had an idea to make use out of axe with fortune enchantment, but that would be silly if player could just place a bunch of wood and destroy it to get much more wood than he had originally

Describe the solution you'd like Have a block modifier (like LOG@NARUTAL or LOG@PLACED). Of course it's up to developers, this is just my proposition.