title: Antlr4 parser not handling custom token types
body: <p>I am migrating my grammar from version 3 to 4.  I recognize that version 4 has listeners and visitors and I plan to use them, but hope to do the migration piece meal.  I want to leave actions intact in my grammar for the time being.<br>
  I am using a custom token, and specify it using TokenLabelType in the option section of the grammar.  However, the generated code uses a 'match()' method which doesn't get promoted to my custom token, causing the java compilation to fail.
  I also noticed the 'start' property of a token is not promoted to the custom token type either.
  Is there something else I should do to properly use custom tokens in my code?</p>