Improve chicken-install cyclic dependencies error

[Diego]

Currently with cyclic dependencies in a complex egg file, chicken-install throws an error like e.g.:

Error: cyclic dependencies: ((math.polynomial.chebyshev math.flonum.functions math.racket-shim math.base) (math.functions.stirling-error math.base math.flonum.functions math.flonum.polyfun math.polynomial.chebyshev math.racket-shim) (math.vector.base) (math.number-theory.tangent-number) (math.number-theory.quadratic-residues math.number-theory.divisibility math.number-theory.modular-arithmetic math.number-theory.base math....

This is quite hard to make sense of (and not to mention incomplete)