Feature/scroll (#22)

* base scroll implementation

* add scroll collection example
mofidy scrolls, fix callback calls

* unhover button if start swipe
notify input components on swipe

* add node center offset, calc by pivots
modify with with node center scroll (to correct scroll to point)

* Refactor, add some docs

* fix: set_pos on end on scroll

* add gui.animate speed in settings

example/scroll.collection

@@ -0,0 +1,37 @@
+name: "default"
+scale_along_z: 0
+embedded_instances {
+  id: "scroll"
+  data: "components {\n"
+  "  id: \"scroll\"\n"
+  "  component: \"/example/scroll/scroll.gui\"\n"
+  "  position {\n"
+  "    x: 0.0\n"
+  "    y: 0.0\n"
+  "    z: 0.0\n"
+  "  }\n"
+  "  rotation {\n"
+  "    x: 0.0\n"
+  "    y: 0.0\n"
+  "    z: 0.0\n"
+  "    w: 1.0\n"
+  "  }\n"
+  "}\n"
+  ""
+  position {
+    x: 0.0
+    y: 0.0
+    z: 0.0
+  }
+  rotation {
+    x: 0.0
+    y: 0.0
+    z: 0.0
+    w: 1.0
+  }
+  scale3 {
+    x: 1.0
+    y: 1.0
+    z: 1.0
+  }
+}