split painter and context classes in nvwidgets.pas into separate source file

fixed compilation example.pp
renamed context and painter source files to be more clear


git-svn-id: https://svn.code.sf.net/p/lazarus-ccr/svn@2248 8e941d3f-bd1b-0410-a28a-d453659cc2b4

components/nvidia-widgets/examples/widget_test.pp

@@ -3,9 +3,8 @@ program widget_test;
 {$mode objfpc}{$H+}
 
 uses
-  Classes, SysUtils,
-  GLut, GL, GLu,
-  nvWidgets, nvGLWidgets, nvBaseFont, nvGlutWidgets, GLFreeTypeFont, GLUTBitmapFont;
+  Classes, SysUtils, GLut, GL, GLu, nvGLPainter,
+  nvGlutContext, GLFreeTypeFont, GLUTBitmapFont, nvTypes;
 
 var
   ui: GlutUIContext;