Merge pull request #71 in G/fastr from...

Merge pull request #71 in G/fastr from ~LUKAS.STADLER_ORACLE.COM/fastr:feature/various_changes4 to master

* commit '4524c682':
  enable passing test
  fix more ReadVariableNode calls with null frames
  special case in RMissingHelper for eager promises
  update cached function in RCallNode generic case
  do not produce optimized promises in RCallNode generic case
  unwrap VirtualEvalFrames when creating environments
  never call ReadVariableNode without frame (can lead to NPE during promise evaluation)
  modify lapply to simulate the correct call structure
  provide "Ignore Whitespace" flag for tests
  add output for new lexer test
  various cleanups
  properly throw recognizer errors from the lexer
  various small fixes (imports, unused fields)
  enable passing tests