new module Diagrams.TwoD.Path.IteratedSubset

For creating fractal trails based on the "iterated subset"
construction, iteratively replacing segments with a given seed pattern.
be more precise about LANGUAGE pragmas in IteratedSubset.hs
import Diagrams.Core.Points to make GHC < 7.6 happy re: V (Point a) instance
deal better with zero-length segments
Merged cabal file.