modifies the hollow metrics API; that'll probably be implemented soon
adds init stages
changes SSatoms to not abuse its `initialized` variable
closes#6858
# why?
non-player facing
we're going to need fast lookups for "is this thing in range of this
other thing" at some point, for things like telecomms
this current solution consumes about 16KB per reservation level
we also add the capability to use spatial grids to quickly get atoms on
a level.
spatial grids are also at 16KB per grid, per world level
all in all worth it in my opinion.
