FastR Grid: savePlot, dev.cur, .Device and .Devices support

.../truffle/r/library/fastrGrid/FastRGridExternalLookup.java

...c/com/oracle/truffle/r/library/fastrGrid/GridContext.java

...src/com/oracle/truffle/r/library/fastrGrid/GridState.java

...rc/com/oracle/truffle/r/library/fastrGrid/LGridDirty.java

...src/com/oracle/truffle/r/library/fastrGrid/LInitGrid.java

.../src/com/oracle/truffle/r/library/fastrGrid/ViewPort.java

...ffle/r/library/fastrGrid/device/BufferedJFrameDevice.java

...oracle/truffle/r/library/fastrGrid/device/ImageSaver.java

...acle/truffle/r/library/fastrGrid/device/JFrameDevice.java

...oracle/truffle/r/library/fastrGrid/grDevices/DevCurr.java

...fle/r/library/fastrGrid/grDevices/InitWindowedDevice.java

...ruffle/r/library/fastrGrid/grDevices/R/fastrGridDevices.R

...racle/truffle/r/library/fastrGrid/grDevices/SavePlot.java

...le/r/library/fastrGrid/graphics/RGridGraphicsAdapter.java