Merge pull request #116 in G/fastr from release/paper_performance_evaluation to master

* commit '5d66fafd':
  remove obsolete comment
  keep better names for functions during code duplication in RASTBuilder
  simplification in WrapDefaultArgumentNode
  only use one type of inline cache in PromiseHelperNode
  simplify ArgumentsStatePush
  unwrap promises for stable lookups in FrameSlotChangeMonitor
  small simplification in ReadVariableNode
  refactor Missing to not use the generic inline cache node
  improve Transpose (better treatment of attributes)
  remove TruffleBoundaries in Transpose
  refactor MersenneTwister