pkgtest: refactor to use internal GNU R when possible; misc other changes for daily recommended packages test

Merge pull request #422 in G/fastr from ~STEPAN.SINDELAR_ORACLE.COM/fastr:feature/replace-refactoring to master

* commit '3a5fb0c7':
  ReplacementBlockNode -> ReplacementDispatchNode
  Create special replacement even for <<-
  RCodeBuilder has context with temp var names start index
  Additional list extract tests
  Replacement executes the target first to specialize
  Replacement refactoring

* commit 'ac6d0bb8':
  install order matters for recommended packages

* commit '6031acb5':
  mx.fastr: remove nocompile in _set_graal_options
  remove redundant mx rcmplib
  support jars and dirs in DefaultResourceHandlerfactory
  add explicit method for accessing directory "resources"
  mx_fastr_dists: add doc comment
  properly ensure that recommended packages can be built in all situations and are included in the release

plus remove unnecessary try-finally and obsolete TODO comment

Now when the reading and writing of the target is responsibility of
ReplacementNode, SpecialReplacementNode works even with <<- (super)

Instead of having static variable with this value, it is part of RCodeBuilder
and transitively part of RContext.

The ReplacementBlockNode executes RHS and the target and
then executes ReplacementNode, which can specialize on
target value. In the default case ReplacementNode creates
nodes that handle replacement in the same way as before:
SpecialReplacementNode and GenericReplacementNode.

Replacements are broken down to individual calls lazily on first execution.
This is done by new ReplacementBlockNode, which executes RHS store to tmp
variable then the actual replacement and then it returns the RHS value.

ReplacementBlockNode creates the node for actual replacement depending on the
replacement structure: if all the calls are specials, it creates
ReplacementNodeSpecial, which takes advantage of the properties of specials.
Otherwise it creates regular replacement node that executes exactly the same
function calls as GnuR would.

Merge pull request #446 in G/fastr from ~STEPAN.SINDELAR_ORACLE.COM/fastr:feature/fixes-for-jvmtrend2 to master

* commit 'b21c05cd':
  Removed flag forNextMethod from argument matching
  Tests for NextMethod argument matching
  Covcor converted to cast pipelines + tests
  Varargs related methods moved from ArgumentsSignature to new class VarArgsHelper

The flag seems to be not needed anymore since we now do the argument matching
for NextMethod in more generic way.

properly ensure that recommended packages can be built in all situations and are included in the release

* commit 'a073465a':
  suppress jdk_tools.jar in fastr-release

Merge pull request #447 in G/fastr from ~MICK.JORDAN_ORACLE.COM/fastr:remove_rconnection_type to master

* commit '91a7cb57':
  AsCharacterFactor: handle change to InheritsNode
  remove the special handling of RConnection

* commit '41f79d8c':
  fix install of recommended packages on clean build

* commit 'd415f905':
  changes for R-3.3.0 compatibility

Merge pull request #435 in G/fastr from ~MICK.JORDAN_ORACLE.COM/fastr:feature/add-recommended to master

* commit '1f30a30b':
  build/install recommended packages if FASTR_RELEASE is set; discover R version dynamically

Merge pull request #445 in G/fastr from ~LUKAS.STADLER_ORACLE.COM/fastr:bugfix/revert_constantnode to master

* commit 'c9f38cfc':
  fix the TruffleObject-related assertion in ConstantNode

Merge pull request #444 in G/fastr from ~STEPAN.SINDELAR_ORACLE.COM/fastr:feature/fixes-for-jvmtrend to master

* commit '7a4dc92a':
  Argument matching for NextMethod target
  Covcor external: support arguments casting
  Remove redundant test in assert

* commit '9badee5c':
  terminate process if initial language initialization fails
  fix mkdtemp bug

NextMethod can have additional arguments, those are combined with the arguments
coming from the callsite of the S3 dispatch method. Additional arguments with
the same name override the callsite arguments, and unmatched arguments (i.e.
default values) of the caller of NextMethod are ignored.