various small changes and cleanups

...e/src/com/oracle/truffle/r/engine/interop/RContextMR.java

...c/com/oracle/truffle/r/ffi/impl/common/Generic_Tools.java

...om/oracle/truffle/r/library/fastrGrid/GridColorUtils.java

...ffle/r/library/fastrGrid/device/awt/Graphics2DDevice.java

...le/r/nodes/builtin/base/printer/ComplexVectorPrinter.java

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

...le/r/nodes/builtin/base/printer/TruffleObjectPrinter.java

....nodes/src/com/oracle/truffle/r/nodes/unary/CastNode.java

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

...acle/truffle/r/runtime/data/model/RAbstractContainer.java

.../src/com/oracle/truffle/r/runtime/nodes/RCodeBuilder.java

.../src/com/oracle/truffle/r/runtime/nodes/RSyntaxUtils.java