Resolve rewrite of pixelDensity to settings.

Per https://github.com/processing/processing4/issues/58, pixelDensity should run in settings and currently results in failure if used in static context. This will rewrite pixelDensity into the setting section if found in static or settings context. Adds unit tests for both scenarios.

java/test/processing/mode/java/ParserTests.java

@@ -378,6 +378,16 @@ public class ParserTests {
     expectGood("packageTest", true, Optional.of("test.subtest"));
   }
 
+  @Test
+  public void testStaticPixelDensity() {
+    expectGood("staticpixeldensity");
+  }
+
+  @Test
+  public void testParamPixelDensity() {
+    expectGood("parampixeldensity");
+  }
+
   private static boolean compile(String id, String program) {
     // Create compilable AST to get syntax problems
     CompilationUnit compilableCU = JdtCompilerUtil.makeAST(