Merge branch 'feature/ffi' of...

...ngine/src/com/oracle/truffle/r/engine/shell/RCommand.java

...gine/src/com/oracle/truffle/r/engine/shell/REmbedded.java

com.oracle.truffle.r.native/fficall/src/jni/Rembedded.c

com.oracle.truffle.r.native/fficall/src/jni/Rinternals.c

com.oracle.truffle.r.native/fficall/src/jni/rffiutils.c

com.oracle.truffle.r.native/fficall/src/jni/rffiutils.h

...iltin/src/com/oracle/truffle/r/nodes/builtin/base/Gc.java

...e.ffi/src/com/oracle/truffle/r/runtime/ffi/RFFIUtils.java

...rc/com/oracle/truffle/r/runtime/ffi/jnr/JNI_CallRFFI.java

...runtime/src/com/oracle/truffle/r/runtime/RCmdOptions.java

...time/src/com/oracle/truffle/r/runtime/RInternalError.java

...fle.r.runtime/src/com/oracle/truffle/r/runtime/Utils.java

com.oracle.truffle.r.test.native/embedded/src/main.c

...fle.r.test.native/packages/testrffi/testrffi/R/testrffi.R

...e.r.test.native/packages/testrffi/testrffi/src/testrffi.c