fix broken download link
Merge pull request #481 from shinpei/README-fix-download-link

fix broken download link
BasicSemanticChecks.checkGrammarName: allow null filenames.

checkGrammarName assumes that all grammars come from actual files, but
grammars loaded using Tool.parseGrammarFromString use input streams
without source file names. This patch changes checkGrammarName to only verify
that grammar names and file names correspond when a file name is
available.
Add aphyr (Kyle Kingsbury) to contributors list
Mark Recognizer.getTokenErrorDisplay as deprecated (fixes #480)
Add regression test for issue #433
Updated RuleFunction.addContextGetters to support multiple alternatives with the same label (fixes #433)
Add regression test for #469
Fix lexerActionExecutor not being preserved when returning from a rule invocation in the lexer (fixes #469)
Properly encapsulate LexerATNConfig.lexerActionExecutor, and mark as final
Add missing @Nullable annotations
Update the runtime to build XPathLexer with ANTLR 4.2
Fix paths to online binaries in build.xml
Merge pull request #502 from sharwell/fix-480

Mark Recognizer.getTokenErrorDisplay as deprecated (fixes #480)
Add regression test for issue #509
Make sure to consider context for the SLL precedence filter (fixes #509)
Add a comment describing a possible future optimization to applyPrecedenceFilter
Merge pull request #510 from sharwell/fix-509

Fix 509
Merge pull request #503 from sharwell/fix-469

Fix 469
Merge pull request #504 from sharwell/update-xpathlexer

Update xpathlexer