- the ugly AE::timer 0, 0, hacks w.r.t. mutate_... should be fixed!
- recursive mutates should be handled somehow.
- change #!/opt/perl.. to something more portable.
- make ambient light configurable in the client.

- 1. sort chunk updates by distance to player.
   - client AND server!
  2. make the client display/have blocking materialization
     blocks to prevent player from entering an un-updated block
  4. dont kill compiled chunks if they are already compiled. just
     update them. => prevent empty chunks from being updated,
     but they should be like blocking anyway!
  3. tell client to teleport player to free location
