`blockgame.register_node` now works both when the provided name includes
a mod name, and when it doesn't.
previously, including a mod name would break things, making the actual
name used for registration include the mod name twice.
loose nodes are now automatically registrered when their settled
counterparts are. also rewrite a small amount of wrapper code and node
registration to work with this.
the api function `blockgame.register_node` will now emit events before
and after registering a node, allowing for other code to react to and
affect node registration.
make the wrapper `blockgame.register_node` make reasonable assumptions
that make node registration more convenient.
change other code to take advantage of that change.
also remove the `blockgame.reg_simple_node` utility since it's now
redundant.
