Registers new action
@param {String} name Action name
@param {Function} fn Action function
@param {Object} options Custom action options:<br>
<b>label</b> : (<code>String</code>) – Human-readable action name.
May contain '/' symbols as submenu separators<br>
<b>hidden</b> : (<code>Boolean</code>) – Indicates whether action
should be displayed in menu (<code>getMenu()</code> method)

@memberOf actions
function(name, fn, options) {
			name = name.toLowerCase();
			options = options || {};
			if (!options.label) {
				options.label = humanizeActionName(name);
			}
			
			actions[name] = {
				name: name,
				fn: fn,
				options: options
			};
		}