FastR Grid: honor fill color + GUI framework independent color representation

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

...rary/src/com/oracle/truffle/r/library/fastrGrid/GPar.java

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

...y/src/com/oracle/truffle/r/library/fastrGrid/LPoints.java

...le/truffle/r/library/fastrGrid/device/DrawingContext.java

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

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

...truffle/r/test/library/fastrGrid/GridColorUtilsTests.java

mx.fastr/copyrights/overrides

mx.fastr/mx_fastr.py