[GR-8319] More work on R embedding interface.

.gitignore

ci.hocon

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

...com/oracle/truffle/r/ffi/codegen/FFIVariablesCodeGen.java

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

.../truffle/r/ffi/impl/nfi/HandleNFIUpCallExceptionNode.java

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

...pl/src/com/oracle/truffle/r/ffi/impl/nodes/MiscNodes.java

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

...rc/com/oracle/truffle/r/ffi/impl/nodes/TryRfEvalNode.java

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

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

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

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

...e.truffle.r.native/fficall/src/common/rffi_upcallsindex.h

...ve/fficall/src/truffle_common/Rinternals_truffle_common.h

...acle.truffle.r.native/fficall/src/truffle_nfi/Rembedded.c

com.oracle.truffle.r.native/version.source

...uffle/r/nodes/builtin/base/printer/AttributesPrinter.java

...cle/truffle/r/nodes/builtin/base/printer/ListPrinter.java