LT-67 Creating utility helpers for lesiontracker package and implementing servers listing

Packages/lesiontracker/client/helpers/logical.js

@@ -0,0 +1,35 @@
+Template.registerHelper("choose", function() {
+    let result;
+    _.each(arguments, value => {
+        if (result || value instanceof Spacebars.kw) return;
+        value && (result = value);
+    });
+    return result;
+});
+
+Template.registerHelper("bool", function(value) {
+    return !!value;
+});
+
+Template.registerHelper("equals", function(a, b) {
+    return a === b;
+});
+
+Template.registerHelper("not", function(value) {
+    return !value;
+});
+
+Template.registerHelper("and", function() {
+    let result = true;
+    _.each(arguments, value => value || (result = false));
+    return result;
+});
+
+Template.registerHelper("or", function() {
+    let result = false;
+    _.each(arguments, value => {
+        if (value instanceof Spacebars.kw) return;
+        value && (result = true);
+    });
+    return result;
+});