DrScheme Jr is split up into 3 files:
         
  - drscheme-jr.ss 
     This is the main file that loads the signatures, defines a settings (from userspace/basis.ss)
     and starts drscheme-jr.
     
  - core.ss
     This file defines a function make-go that accepts a unit that imports 
     three units matching the signatures: prims^ (defined in core.ss) 
     userspace:basis^, and mzlib:core^ and exports drscheme-jr:settings.
     The function make-go returns a thunk which starts drscheme-jr.
     
     This file is intended to be used with the launchers that DrScheme creates.
     
  - go.ss
     This file loads drscheme-jr.ss, sets the current-load-relative and
     current-require-relative-collection parameters and calls go.
