support multi-line shell input

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

...c/com/oracle/truffle/r/nodes/builtin/RBuiltinPackage.java

...oracle/truffle/r/nodes/builtin/base/BrowserFunctions.java

...m/oracle/truffle/r/nodes/function/DispatchedCallNode.java

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

...ntime/src/com/oracle/truffle/r/runtime/data/RPromise.java

...ffle.r.shell/src/com/oracle/truffle/r/shell/RCommand.java

...l/src/com/oracle/truffle/r/shell/RJLineConsoleReader.java