Add an accessLevel parser option. Use this to specify the access level
(public, etc) used on the classes and protocols in the generated
parser / lexer / listeners. This required adding the option to
tool.Grammar.parserOptions so that it was known as a valid option, and
to codegen.model.{Recognizer,ListenerFile,VisitorFile} so that it was
available to the template in all the necessary contexts.
The Swift template has been extended to recognize this option, and generate
classes and members using "open", "public" or "internal" as appropriate.
This is only fully implemented for Swift. The option is generic, but
the language-specific templates will need to be updated for any language
that would like similar support.
Closes#1597.
This takes the example from
https://github.com/janyou/Antlr-Swift-Runtime/tree/master/Test and packages
it into an Xcode playground. This allows the user to interact with the
grammar directly inside Xcode, and serves as a live demo of the Swift support.
Update the docs to match.