Added support for planet files by internally reorganizing setup-unit:
Added support for planet files by internally reorganizing setup-unit:

the cc structure once represented a collection to be compiled; now it
represents a directory to be compiled, with different ways of constructing
a cc applying to libraries and collection paths.

original commit: 56358bed791e23498e841586da0bb0901bbe0c2f

mafagafogigante/racket,mafagafogigante/racket,mafagafogigante/racket,mafagafogigante/racket,mafagafogigante/racket,mafagafogigante/racket,mafagafogigante/racket,mafagafogigante/racket,mafagafogigante/racket