Merge pull request #477 in G/fastr from ~LUKAS.STADLER_ORACLE.COM/fastr:feature/specials_tests to master

* commit '0dd47ec8':
  don’t test specials without FastROptions.UseSpecials
  change specials to handle fallbacks in recursive cases via a “special parent” reference, add tests

* commit 'd33e7eb7':
  correct parameters to url builtin (3.3.x)

Merge pull request #474 in G/fastr from ~LUKAS.STADLER_ORACLE.COM/fastr:feature/unserialize_from_pairlist to master

* commit '1fd263b6':
  add tests for “unserialize”, enable passing tests
  unserialize from pairlist without generating source code, cleanup RDeparse

Merge pull request #476 in G/fastr from ~LUKAS.STADLER_ORACLE.COM/fastr:feature/rfiles_caching to master

* commit 'ae2efefd':
  cache in RBuiltinPackage.getRFiles (speeds up context creation)

Merge pull request #475 in G/fastr from ~LUKAS.STADLER_ORACLE.COM/fastr:feature/int_warnings to master

* commit 'edbe9f13':
  report only one warning during double to int conversion

* commit 'd3feecab':
  enable passing tests
  implement ParNode using OperatorNode
  new ParNode to represent parentheses in source code

Merge pull request #472 in G/fastr from ~LUKAS.STADLER_ORACLE.COM/fastr:feature/speedup_tests to master

* commit 'b21dc601':
  use “previousLookups” to speed up FrameSlotChangeMonitor.invalidateAllNames
  minor cleanups

* commit 'e0d2af6e':
  mx.fastr: revert junit_* definitions to allow override

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
  ...

use DoubleVectorPrinter in RDeparse, fix bug in DoubleVectorPrinter that can lead to unnecessary spaces in 1e23 formats