make layout return children
layout as functions
pass in layout as closures
create game world before adding children
call sprite setup manually;
add child layout to level world
factor our create_level
cleanup level
game levels
get levels from world
redo assert
key off file not name
stub create-game
extract new shapes
from language to words
rename file to words
return keys
return all keys if array passed in
words is now a world
remove debugging