Add a way for objects to provide a static constructor

Previously, in NativeTypeList, there was no way to customize how an invalid
instance was constructed. Now, if a subclass of Mixed provides a method named
ConstructInvalidInstance, this will be called instead. For now, this is not
necessary in any native classes, but since this picks up extension objects
as well, it might be useful already.

src/main/java/com/laytonsmith/core/constructs/NativeTypeList.java

@@ -34,6 +34,13 @@ public class NativeTypeList {
 	private static volatile Set<String> nativeTypes;
 	private static Set<FullyQualifiedClassName> fqNativeTypes;
 
+	/**
+	 * The name of the static method in all Mixed classes, which if present, is called when
+	 * getInvalidInstanceForUse is called on that class. The method should return a value of
+	 * that type, and should accept no parameters. The method name is "ConstructInvalidInstance".
+	 */
+	public static String INVALID_INSTANCE_METHOD_NAME = "ConstructInvalidInstance";
+
 	/**
 	 * Given a simple name of a class, attempts to resolve
 	 * within the native types (not user defined types). If the class can't be found, null is returned,
@@ -283,6 +290,9 @@ public static Class<? extends MixedInterfaceRunner> getInterfaceRunnerFor(FullyQ
 	 */
 	public static Mixed getInvalidInstanceForUse(FullyQualifiedClassName fqcn) throws ClassNotFoundException {
 		Class<? extends Mixed> c = getNativeClassOrInterfaceRunner(fqcn);
+		if(ReflectionUtils.hasMethod(c, INVALID_INSTANCE_METHOD_NAME, Mixed.class)) {
+			return (Mixed) ReflectionUtils.invokeMethod(c, null, INVALID_INSTANCE_METHOD_NAME);
+		}
 		if(MEnumType.class.isAssignableFrom(c)) {
 			return getNativeEnumType(fqcn);
 		} else {