Added new strong element to ignite template.

ignite-template.js

@@ -1306,6 +1306,18 @@ class span extends IgniteTemplate {
     }
 }
 
+/**
+ * An ignite template that can be used to construct a strong element.
+ */
+class strong extends IgniteTemplate {
+    /** 
+     * @param  {...String|Number|IgniteProperty|IgniteTemplate} children A series of children to be added to this template.
+     */
+    constructor(...children) {
+        super("strong", children);
+    }
+}
+
 /**
  * An ignite template that can be used to construct an i element.
  */
@@ -2409,6 +2421,7 @@ export {
     hr,
     p,
     span,
+    strong,
     i,
     ul,
     li,