Remove scalastyle test hook

I'm trying to get RocketChip to work with Chisel3 again, and we need to
run in multiple directories.  This fixes the workaround I made earlier
to actually parse the passed command-line arguments so I can emit FIRRTL
in the correct directory.

I can't get this to work when Chisel 3 is installed as a submodule.

Distribution prep1

Fix init in deq io

README instructions for installing with Scala FIRRTL

Fixed comment punctuation and made it clearer that using an init() method for DeqIO and EnqIO initialization is likely to change.

Make the corresponding test run faster by giving it a Counter.

Emit no width instead of <?> for unknown width UInt and SInt literals…

copied machinery from chisel2 build.sbt
added a few intellij lines to gitignore

Chisel tester support

Cleanup comment for finish method in BasicTester, and finishWrapper in TesterDriver.

clean up the test example

Separate assertion failure message from source locator line

Added support for finish method of BasicTester to be overridden in a subclass which allows tester to have clean up and other construction code executed after a user code executed during constructor of that subclass

Add Flipped trait; fix DeqIO, this fix looks good to go

If we end up generalizing Strings, this code should be moved elsewhere.

Note FIRRTL doesn't handle this stuff right, so I'm not committing the
companion test yet.

Make assert failures more informative using macros

Add some Chisel2 driver emulation methods

I don't want to have to maintain a big rocket-chip fork to have it run
through Chisel3, so instead I'm adding back some of the driver routines
that existed in Chisel2.