Merge pull request #203 from ucb-bar/flo_widths

Dreamer backend respects --targetDir directive for VCD dumps.
Tester will now return signed BigInts for SInt peeks.
Handle non-Int data for Tester::peek

Bits may be Flo or Dbl. Handle those cases as well (at least as well
as we used to handle them).
Made all outputs appear properly in flo files, even if used on RHS of := assignments elsewhere.