Introduce structure to the test/ directory

This introduces a clear separation between test data and test
binaries. Test data is moved into test/data, and the test binaries
move into test/src. A new CMake script specific to building the
tests is introduced in /test to slightly clean up the toplevel
one.

As well as tidying things up, this makes the next step trivial...

test/data/json.org/3.json

@@ -0,0 +1,26 @@
+{"widget": {
+    "debug": "on",
+    "window": {
+        "title": "Sample Konfabulator Widget",
+        "name": "main_window",
+        "width": 500,
+        "height": 500
+    },
+    "image": { 
+        "src": "Images/Sun.png",
+        "name": "sun1",
+        "hOffset": 250,
+        "vOffset": 250,
+        "alignment": "center"
+    },
+    "text": {
+        "data": "Click Here",
+        "size": 36,
+        "style": "bold",
+        "name": "text1",
+        "hOffset": 250,
+        "vOffset": 100,
+        "alignment": "center",
+        "onMouseUp": "sun1.opacity = (sun1.opacity / 100) * 90;"
+    }
+}}