* Update Sharpen namespace to Antlr4.Runtime.Sharpen at code generation time

* Support self-closing tags in XML documentation comments
* Use self-closing see tags when the content is just the name of the referenced item
Map Collection.add to Add instead of AddItem
Map java.util.UUID to System.Guid
Merge branch 'sharpen'
Map putIfAbsent to GetOrAdd
Map ArrayDeque and Deque to Stack
Map java.util.Reader to System.IO.TextReader
Merge branch 'sharpen'
Updated version numbers for release 4.3.0
Update version numbers for next development cycle
Merge pull request #61 from sharwell/release/4.3.0

Release/4.3.0