Added hotkey support to viewerbase

Packages/viewerbase/client/components/viewer/hangingProtocolButtons/hangingProtocolButtons.html

@@ -0,0 +1,20 @@
+<template name="hangingProtocolButtons">
+    <button id="previousPresentationGroup" type="button"
+            class="imageViewerCommand btn btn-sm btn-default"
+            data-container="body"
+            data-toggle="tooltip"
+            data-placement="bottom"
+            title="Previous presentation group"
+            disabled="{{ #unless isPreviousAvailable }} true {{ /unless }}">
+        <span class="fa fa-step-backward"></span>
+    </button>
+    <button id="nextPresentationGroup" type="button"
+            class="imageViewerCommand btn btn-sm btn-default"
+            data-container="body"
+            data-toggle="tooltip"
+            data-placement="bottom"
+            title="Next presentation group"
+            disabled="{{ #unless isNextAvailable }} true {{ /unless }}">
+        <span class="fa fa-step-forward"></span>
+    </button>
+</template>

Packages/viewerbase/client/components/viewer/hangingProtocolButtons/hangingProtocolButtons.js

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+Template.hangingProtocolButtons.helpers({
+    'isNextAvailable': function() {
+        var presentationGroup = Session.get('WindowManagerPresentationGroup');
+        var numPresentationGroups = WindowManager.getNumPresentationGroups();
+        return presentationGroup < numPresentationGroups;
+    },
+    'isPreviousAvailable': function() {
+        var presentationGroup = Session.get('WindowManagerPresentationGroup');
+        return presentationGroup > 1;
+    }
+});