Work on refactoring measurements out of Lesion Tracker package

- Removed AssociatedStudies Collection
- Measurement API is generated from configuration files
- Data exchange methods are defined in configuration

Packages/ohif-viewerbase/client/components/viewer/layoutButton/layoutButton.js

@@ -0,0 +1,17 @@
+Template.layoutButton.events({
+    // TODO: Check why 'click' event won't fire?
+    'mousedown .js-dropdown-toggle'(event) {
+        // Select the button and it's target dropdown menu
+        const $button = $(event.currentTarget);
+        const $dropdown = $($button.data('target'));
+
+        // Adjust the dropdown's CSS to properly place it on the page
+        $dropdown.css({
+            top: $button.offset().top + $button.outerHeight() + 'px',
+            left: $button.offset().left + 'px'
+        });
+
+        // Open or close the layout chooser dialog
+        toggleDialog($dropdown);
+    }
+});