unify RLanguage and RPairList, proper implementation of SET_TYPEOF

...fle.r.engine/src/com/oracle/truffle/r/engine/REngine.java

...rc/com/oracle/truffle/r/engine/RRuntimeASTAccessImpl.java

...ngine/src/com/oracle/truffle/r/engine/interop/ListMR.java

...e/truffle/r/engine/interop/RForeignAccessFactoryImpl.java

.../src/com/oracle/truffle/r/engine/interop/RLanguageMR.java

...src/com/oracle/truffle/r/ffi/codegen/FFITestsCodeGen.java

...oracle/truffle/r/ffi/impl/common/JavaUpCallsRFFIImpl.java

...racle/truffle/r/ffi/impl/nodes/AttributesAccessNodes.java

.../src/com/oracle/truffle/r/ffi/impl/nodes/CoerceNodes.java

.../com/oracle/truffle/r/ffi/impl/nodes/ListAccessNodes.java

...l/src/com/oracle/truffle/r/ffi/impl/nodes/RfEvalNode.java

...com/oracle/truffle/r/ffi/impl/upcalls/StdUpCallsRFFI.java

...le/r/library/fastrGrid/graphics/RGridGraphicsAdapter.java

...oracle/truffle/r/library/methods/MethodsListDispatch.java

...om/oracle/truffle/r/library/methods/SubstituteDirect.java

...src/com/oracle/truffle/r/library/stats/CompleteCases.java

...brary/src/com/oracle/truffle/r/library/stats/deriv/D.java

...y/src/com/oracle/truffle/r/library/stats/deriv/Deriv.java

...racle.truffle.r.native/fficall/src/common/inlined_fastr.c

...oracle.truffle.r.native/fficall/src/common/rffi_upcalls.h