Closes #371: Mutli-line string support.

Offers support for multi-line strings with a flag to simulate the feature prior to switching to Java 17 build flags. Note that comments are left in (TODOs) where the switch would be required to support it "natively".

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

@@ -415,4 +415,9 @@ public class ParserTests {
     expectGood("sizeclass");
   }
 
+  @Test
+  public void testMultlineString() {
+    expectGood("multilinestr");
+  }
+
 }