Default to not being ground content.
The few nodes that were registered as ground content shouldn't be considered ground content.
* cut nodes aren't ground content
By default make cut nodes non ground content but allow mods to register theirs as ground content if they want to.
If stairs from stairs mod were crafted before moreblocks was enabled, the old (now aliased) stairs variant is kept in inventory. If the player tried to recycle that stair variant, `inv:contains_item("output", stackname)` would return true as `contains_item` resolves alias names, but `circular_saw:get_cost` would return nil as it's expecting exact `stackname` matches which would later crash due to nil arithmetic.
This PR fixes this issue by resolving alias using `minetest.registered_aliases` table.
`circular_saw:get_cost` should work now in every scenario where `inv:contains_item("output", stackname)` returns true.
The appended '_bottom' is left over from an older naming convention and relies
on an alias to avoid unknown nodes showing up in the saw's left-over bin.
Adds a check to see if recycle stack wouldn't overflow the input stack. If so, then
the items are just put in the recycle slot and they can be taken out again.
Resolves a number of cases where switching stacks of different types of blocks with different counts would cause a corruption in the Player inventory stack count or allow normally unaccepted items into the Saw causing 'unknown' items to be generated in its output.
