adding the .kojo extension for Scala (#3960)

samples/Scala/fib-tree.kojo

@@ -0,0 +1,53 @@
+// Kojo examples (files ending in .kojo) are licensed under The MIT License:
+
+// Copyright (C) 2009-2018 Lalit Pant <pant.lalit@gmail.com> and the Kojo Dev Team.
+
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+
+
+// Example from http://lalitpant.blogspot.in/2012/05/recursive-drawing-with-kojo.html
+// This example is based on Kojo Pictures
+val size = 100
+def S = Picture {
+    repeat (4) {
+        forward(size)
+        right()
+    }
+}
+
+def stem = scale(0.13, 1) * penColor(noColor) * fillColor(black) -> S
+
+clear()
+setBackground(Color(255, 170, 29))
+invisible()
+
+def drawing(n: Int): Picture = {
+    if (n == 1) 
+        stem
+    else 
+        GPics(stem,
+              trans(2, size-5) * brit(0.05) -> GPics(
+                rot(25) * scale(0.72) -> drawing(n-1),
+                rot(25) * trans(0, size * 0.72) * rot(-75) * scale(0.55) -> drawing(n-1)
+            )
+        )
+}
+
+val pic = trans(0, -100) -> drawing(10)
+draw(pic)