Output Format Choice for Tester

[ben-k]

When you use 'peek' and the like in the Tester class, the outputs are in hexadecimal. It would be great if you could optionally have Chisel emit them in decimal, binary, etc., for easier debugging depending on circumstance.

[da-steve101]

This is related to #588 and #589 Essentially formatting of the output. I think the best way to do this is as #588 suggests and optionally make it silent. Can then use scala to print anything out as desired. I don't think there is any difference in ease of use compared to passing in an argument to indicate what to print.

[ben-k]

OK, then I guess this can be closed when #589 is merged in...