fixup errors that occur post-repository2016

[mgatny]

@donmendelson, thank you for this utility. Being familiar with the quality of your work, I was thrilled to find out that it exists! I apologize in advance that my questions and/or proposed fixes in this PR could likely be answered by reading the complete orchestra spec...

Problem: I could not get orchestra2proto to run w/o errors

Solution: I switched the imports from _2016 to _2020, ensured that GroupRefType is considered before ComponentRefType (because GroupRefType is-a ComponentRefType), and defaulted to using the value attr when the sort attr is not present.

Observations/Questions:

• Does a correct orchestra file ever omit sort? This util assumes not.
• Does sort ever differ from value? This PR assumes that if sort is omitted, then value should be used.
• CodeType Suspend has a sort of 4 (i.e. with a space). I assume this is a typo in OrchestraFIXLatest.xml.
• What I'm really going for is FIX Latest, so I'm not sure the _2020 package is the right thing.

[donmendelson]

First, I want to give credit to Greg Malatestinic who made the original contribution.

The namespace was changed when Orchestra v1.0 draft standard was published. "_2020" is correct.

Sort on a code is an optional attribute that represents its position in documentation. It was mistakenly made a string type in v1.0. There is a ticket and PR in fix-orchestra project to change it to numeric in v1.1 RC1.

[mgatny]

Thanks, Don. And thank you, @gmala! This utility is fantastic, and really eases our adoption of orchestra!