Rembedded: add support for Interface callbacks on console

...oracle/truffle/r/engine/shell/EmbeddedConsoleHandler.java

...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/variables.c

...om/oracle/truffle/r/nodes/builtin/fastr/FastRContext.java

...oracle/truffle/r/nodes/builtin/helpers/TraceHandling.java

.../src/com/oracle/truffle/r/runtime/ffi/jnr/JNI_REmbed.java

...com/oracle/truffle/r/runtime/ffi/jnr/JNR_RFFIFactory.java

...le.r.runtime/src/com/oracle/truffle/r/runtime/RError.java

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

...untime/src/com/oracle/truffle/r/runtime/RStartParams.java

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

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

...time/src/com/oracle/truffle/r/runtime/ffi/REmbedRFFI.java

....r.runtime/src/com/oracle/truffle/r/runtime/ffi/RFFI.java

com.oracle.truffle.r.test.native/Makefile

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