Add test-specific scalastyle config

Add Scala-land unit tests for Reg

Whitespace scalastyle fixes for tests

Add curly braces around that one last if block

Add explicit types for public methods

Scalastyle fixes involving changing code

Make if / else braces style conformant to Scalastyle checker

Whitespace / comment style fixes

Add operators to Scalastyle configuration MethodNamesChecker ignore list

Change scalastyle checker to 120 cols limit

Change scalastyle to check for shorter RISC-V style license notice.

Core.scala API documentation

Remove old Literal object; fold the parseLit into UInt

Update README with Mem(seqRead) -> SeqMem()

Handle IllegalArgumentExcetions that mean a cloneType is needed

When trying to cloneType() on classes that take a builtin (like Int),
we get an IllegalArgumentException instead of a InvocationTargetException.
This change prints a nice error message instead of a stack trace.

Type hierarchy diagram -- looks good

Avoid:

    [error] (run-main-0) java.lang.UnsupportedOperationException: empty.reduceLeft
    java.lang.UnsupportedOperationException: empty.reduceLeft

when invoked via chiselMain() with no Parameters.

Flip Mem/SeqMem argument order; deprecate old ordering

Eliminate outdated parts of readme, add skeleton for new format