0.0.2-rc3

1. Fix chunk relighting
   In order to make relighting more reliable, move the
   emptiness map lookups to their own cache. This allows us
   to not clobber/use emptiness map values for chunks that were
   not relight during the call.
   More importantly, fix a typo where we supplied the wrong chunk
   argument to the emptiness change function for chunk neighbours -
   this caused the nibbles for the target chunk to be clobbered.

2. Fix broken edge checks
   While edge checks are not currently used, it doesn't mean
   they should be broken. Edge checks should be able to happen
   on null nibbles for block lighting (sky lighting will not have
   nibbles marked null during edge checks).

3. Make handleEmptySectionChanges non-relaxed serverside
   For the server, it should be that the chunks in 1 radius are
   loaded during this call.

4. Fix incorrect neighbour nibble init logic
   We need to be copying the whole array, not just
   the first 9 values.

5. Fix potential missed updateVisible calls
   rewriteNibbleCacheForSkylight could set a value
   in the cache to null and not update the nibble.
   Now the call will call updateVisible when
   removing nibbles from the cache.

6. Fix skylight propagation on the -1 chunk section
   Allow sources to be set up on y=-16, and fix light
   retrieval for y < -16