Merge pull request #463 in G/fastr from ~LUKAS.STADLER_ORACLE.COM/fastr:feature/various_performance to master

* commit 'ebab0763': (22 commits)
  fix various faulty tests
  fix UpdateLevels to handle NULL
  replacement special calls return the rhs value with the exception if it was already evaluated
  introduce RNode.voidExecute
  do not re-evaluate rhs upon fallback to generic in special replacement
  avoid REGULAR write to current frame for super assignments
  changed param type in SpecialsUtils
  omit temp store of target for special replacments
  simplify DoubleVectorPrinter.encodeReal
  use DoubleVectorPrinter in RDeparse, fix bug in DoubleVectorPrinter that can lead to unnecessary spaces in 1e23 formats
  introduce Utils.isInterned
  move handling of replacement temp vars into special/generic replacement nodes
  further cleanups in replacement and write variable nodes
  operators are RSyntaxLookup instead of RSyntaxElement (in OperatorNode)
  provide better source sections in various places
  remove RSyntaxNodeVisitor
  refactoring ReplacementNode
  introduce OperatorNode as baseclass for special nodes masquerading as calls
  no need for hasBraces in RDeparse
  provide specializations for AccessFieldSpecial and UpdateFieldSpecial that can handle a changing “names” attribute
  ...