Merged LesionTracker and OHIF Viewer, refactored out common components

Packages/viewerbase/components/viewer/imageViewerViewport/imageViewerViewport.html

@@ -0,0 +1,13 @@
+<template name="imageViewerViewport">
+    <div class='imageViewerViewport'
+        oncontextmenu='return false;'
+        unselectable='on'
+        onselectstart='return false;'>
+    </div>
+    <div class='viewportInstructions'>
+        Please drag a stack here to view images.
+    </div>
+    {{ >loadingIndicator }}
+    {{ >viewportOverlay }}
+    {{ >viewportOrientationMarkers }}
+</template>