create contexts via TruffleVM, query "echo" via "getOption(...)" in REPL

...gine/src/com/oracle/truffle/r/engine/RContextFactory.java

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

...ine/src/com/oracle/truffle/r/engine/TruffleRLanguage.java

...ine/src/com/oracle/truffle/r/engine/repl/RREPLServer.java

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

...src/com/oracle/truffle/r/engine/shell/RscriptCommand.java

.../src/com/oracle/truffle/r/library/fastr/FastRContext.java

...es.test/src/com/oracle/truffle/r/nodes/test/TestBase.java

...rc/com/oracle/truffle/r/nodes/instrument/RInstrument.java

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

...e/src/com/oracle/truffle/r/runtime/RRuntimeASTAccess.java

...src/com/oracle/truffle/r/runtime/context/ContextInfo.java

...time/src/com/oracle/truffle/r/runtime/context/Engine.java

...me/src/com/oracle/truffle/r/runtime/context/RContext.java

.../src/com/oracle/truffle/r/test/generate/FastRSession.java