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-hanging-protocols/client/components/previousPresentationGroupButton/previousPresentationGroupButton.html

@@ -0,0 +1,19 @@
+<template name="previousPresentationGroupButton">
+    <div id="{{this.id}}"
+         class="toolbarSectionButton rp-x-1 {{this.classes}} {{activeClass}} {{ #if previousNotAvailable }}disabled{{ /if }}"
+         title="{{this.title}}"
+         disabled="{{ #if previousNotAvailable }}true{{ /if }}">
+        <div class="svgContainer">
+        {{ #if this.svgLink }}
+        <svg>
+            <use xlink:href={{this.svgLink}}></use>
+        </svg>
+        {{ else }}
+            <i class={{iconClasses}}></i>
+        {{ /if }}
+        </div>
+        <div class="buttonLabel">
+            {{this.title}}
+        </div>
+    </div>
+</template>

Packages/ohif-hanging-protocols/client/components/previousPresentationGroupButton/previousPresentationGroupButton.js

@@ -0,0 +1,44 @@
+Template.previousPresentationGroupButton.helpers({
+    /**
+     * Check if an earlier stage exists for the user to switch to
+     *
+     * @returns {boolean} Whether or not an earlier stage exists
+     */
+    previousNotAvailable() {
+        // Run this helper whenever the ProtocolEngine / LayoutManager has changed
+        Session.get('LayoutManagerUpdated');
+
+        // If no ProtocolEngine has been defined yet, stop here
+        if (!ProtocolEngine) {
+            return;
+        }
+
+        // Return whether or not the current stage is the first stage
+        return ProtocolEngine.stage === 0;
+    }
+});
+
+Template.previousPresentationGroupButton.events({
+    /**
+     * Switch to the previous Presentation group
+     *
+     * @param event The click event on the button
+     */
+    'click #previousPresentationGroup'(event) {
+        // If no ProtocolEngine has been defined yet, do nothing
+        if (!ProtocolEngine) {
+            return;
+        }
+
+        // Stop here if the tool is disabled
+        if ($(event.currentTarget).hasClass('disabled')) {
+            return;
+        }
+
+        // Hide the button's Bootstrap tooltip in case it was shown
+        $(event.currentTarget).tooltip('hide');
+
+        // Instruct the ProtocolEngine to switch to the next stage
+        ProtocolEngine.previousProtocolStage();
+    }
+});