removed extraneous code from world
commented out convenience functions in core
now only stores last world in each round when building simulation

also did significant refactoring, including changing
variable names from 'round' to 'combined-world' before
going through the simulation-pass, and 'sim-world' afterwards.

Soon, we'll make the worlds coming out of 'sim-world' a lot less
verbose.
changed 'make-it-so' function in core so it takes fast-forward and fps parameters
made some unnecessary thunks into resolved values in core
uncommented and spruced up pprinting convenience functions in core
changed seconds elapsed in game world report from float to decimal
added report for seconds elapsed in real world
now removing brain from all robots in sim-world construction; easier to send by json