Filezoo, 15.2: DirStats static rewrite

Just finished the first pass of rewriting public class DirStats as public static class FSDraw. FSDraw does no filesystem access, no sorting and no layout creation. It runs through the tree of FSEntries given to it, and should have predictable performance.

What I will do next is disable parent dir drawing in DirStats to make its layout equal to the current FSDraw stuff, then write a simple FSCache that creates FSEntries for a directory. Then replace the CurrentDir.Draw in Filezoo with FSDraw.Draw. Small seamless changes...