feature: additional map edge blocks behaviors

[M0ahgra]

options to make the blocks outside the map (both the top layer, and bottom layer independantly choose-able) behave like normal blocks (except for being able to break them), such as water blocks that you can swim in, or solid blocks you can stand on. this is actually much like indev which let you walk outside the map, and also in indev if there was lava at the bottom of the map you could swim downwards thru it forever below the map. in indev, attempting to break blocks outside the map gave the breaking animation but didnt break the block. classicube actually (seems to?) have a feature like this where some maps on servers have their edge-of-map collision removed so you can fall into an endless void. this option may give mapmakers a little bit more options.

[backtick82]

The edge-of-map collision is removed via setting the collide of blockid 7 (bedrock) to 0 (which i think could be a bug)

[Goodlyay]

The edge-if-map collision is removed via setting the collide of blockid 7 (bedrock) to 0 (which i think could be a bug)

This is intentional