Bump plugin versions.

This would ultimately get DCE'd, but it's easy enough to not
generate the dead code in the first place.

- Remove power-of-2 restriction on count
- Avoid redundancy between lockIdx and chosen signals, reducing area
- Infer locked from lockCount, rather than maintaining separate state
- Reduce FIRRTL node count in several places
- Special-case simple Arbiter, which avoids serializing the computation
  of io.chosen with io.out.valid/bits.  This lops off a few FO4 delays
  at no area cost, and actually reduces area if io.chosen isn't used.

It was never meant to be a public API, and the implementation left
something to be desired.

It doesn't really make sense to create a one-hot result then follow it
with a decoder.  It's more performant to use a PriorityEncoder followed
by a comparator.  Discourage the former by returning Seq, not Vec.

In Chisel2, it seems the return type was originally Seq, but was at some
point inadvertently changed to Vec.

Scalastyle "scalastyle-sbt-plugin" % "0.7.0) dies with:
    [error] .../chisel3/src/main/scala/Chisel/Data.scala: Expected token RBRACKET but got Token(XML_START_OPEN,<,4360,<)
    [error] .../chisel3/src/main/scala/Chisel/Driver.scala: Expected token RBRACKET but got Token(XML_START_OPEN,<,3418,<)
    ...
Upgrade to "scalastyle-sbt-plugin" % "0.8.0"
(and bump the the others to "current" versions while we're here.)

Sign- or zero-extend the argument to match.

For internal purposes only.  Avoids redundant code emission for assertions.

Fix assert

Add =/= to the ignoreRegex for MethodNamesChecker.

Scalastyle cleanup - no functional differences.

Add pointer to Chisel3 compatibility on Chisel2 README.

Verilator suppress warnings

show verilator command on starndard out
Changed --Wno-fatal to -Wno-fatal (double dash became single dash) in accordance with verilator docs
println the verilator command to the standard out, so it can be seen along with the various compiler calls

Print a better message on constant width failures

I'm getting this error and the message is awful.

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