added support for text-based toolbar options

Added the ability to pass innerHTML text for toolbar icon anchors.

src/js/simplemde.js

@@ -108,6 +108,10 @@ function createIcon(options, enableTooltips, shortcuts) {
 		}
 	}
 
+	if(options.innerHTML) {
+		el.innerHTML = options.innerHTML;
+	}
+	
 	el.tabIndex = -1;
 	el.className = options.className;
 	return el;
@@ -2025,4 +2029,4 @@ SimpleMDE.prototype.toTextArea = function() {
 	}
 };
 
-module.exports = SimpleMDE;
+module.exports = SimpleMDE;