Added 9-patch and example for that.

examples/intro/patch.d

@@ -0,0 +1,22 @@
+/// This example shows how to draw a 9-patch texture in Parin.
+
+import parin;
+
+auto atlas = TextureId();
+auto patchAtlasArea = Rect(5 * 16, 1 * 16, Vec2(16 * 3));
+
+void ready() {
+    lockResolution(320, 180);
+    atlas = loadTexture("atlas.png");
+}
+
+bool update(float dt) {
+    auto start = Vec2(8);
+    // Draw a 9-patch texture with a size based on the mouse position.
+    drawTexturePatch(atlas, patchAtlasArea, Rect(start, mouse - start), true);
+    return false;
+}
+
+void finish() { }
+
+mixin runGame!(ready, update, finish);