Merge pull request #668 in G/fastr from ~MICK.JORDAN_ORACLE.COM/fastr:feature/baserffi-refactor to master

* commit '942b6a66':
  rffi: refactor more RFFI interfaces into one Node per function
  rffi: refactor BaseRFFI into one node per function

Merge pull request #652 in G/fastr from ~STEPAN.SINDELAR_ORACLE.COM/fastr:feature/grid-support to master

* commit '51a8d559':
  Initial grid package support
  Fix: make tests independent on whether grid package is loaded or not

Merge pull request #675 in G/fastr from ~STEPAN.SINDELAR_ORACLE.COM/fastr:fix/range-honors-finite-arg to master

* commit 'd19add0a':
  range honors the 'finite' parameter

Merge pull request #664 in G/fastr from ~LUKAS.STADLER_ORACLE.COM/fastr:feature/visible_execute to master

* commit '2bee338b':
  introduce visibleExecute and use whereever visibility is required

Merge pull request #669 in G/fastr from ~MICK.JORDAN_ORACLE.COM/fastr:feature/rffi-remove-gvars to master

* commit 'bb6d88bc':
  rffi: remove unused global variables

Note: for some classes used in the tests like 'unit' grid adds S3 methods,
which are not removed even if the package is unloaded.

* commit 'b587e7da':
  rfffi: simplify factory creation

Merge pull request #665 in G/fastr from ~STEPAN.SINDELAR_ORACLE.COM/fastr:feature/paste-s3-dispatch to master

* commit '599c4c23':
  Fix: forgotten ProfiledCastNode in Quantifier
  paste and paste0 use as.character internally

Merge pull request #672 in G/fastr from ~LUKAS.STADLER_ORACLE.COM/fastr:feature/remove_materialize_shared to master

* commit '72ac8c95':
  don’t use sequences in vector fast paths

* commit '49468004':
  added builtin function "is.single"

* commit '28e7013d':
  typos in documentation

Merge pull request #662 in G/fastr from ~LUKAS.STADLER_ORACLE.COM/fastr:feature/force_dispatch_args to master

* commit '0e08476d':
  force promises in special call arguments where dispatch would force them anyway

Merge pull request #663 in G/fastr from ~LUKAS.STADLER_ORACLE.COM/fastr:feature/access_nodes to master

* commit '9bb8a7e1':
  AccessSlotNode and UpdateSlotNode don’t need to be RNodes

* commit '85a20b5d':
  CharSXPWrapper as TruffleObject
  rffi: rewrite all global variables to function calls

* commit 'f92513df':
  generated expected output messages
  c/rbind adds NULL dimnames even if not necessary
  deparse adds too many right parentheses when structure expressions has more attributes

Merge pull request #660 in G/fastr from ~LUKAS.STADLER_ORACLE.COM/fastr:feature/meta_tck_tests to master

* commit 'e3853c46':
  implement TCK tests for findMetaObject and findSourceLocation

* commit 'f038d78f':
  Sharing documentation converted to Markdown
  Cast pipelines documentation converted to Markdown

* commit 'fbec5d38':
  Forwarded types analyser for cast pipelines added