This is a merge between the upstream-intervals and master

as of 9/13/2019.
CheckWidths was radically different, I used the upstream-intervals as the base
I added
//TODO:MERGE:CHICK ...
in a number of places where I was uncertain
Following tests failing still
[error] 	firrtlTests.interval.IntervalSpec
[error] 	firrtlTests.fixed.RemoveFixedTypeSpec
[error] 	firrtlTests.transforms.InferWidthsWithAnnosSpec
[error] 	firrtlTests.fixed.FixedTypeInferenceSpec
[error] 	firrtlTests.InternalErrorSpec