Expose formatParameter as a formatter (#546)

This allows custom themes to override it

Author: arv

lib/output/util/formatters.js

@@ -26,13 +26,13 @@ module.exports = function (getHref) {
    * @param {boolean} short whether to cut the details and make it skimmable
    * @returns {string} formatted parameter representation.
    */
-  function formatParameter(param, short) {
+  formatters.parameter = function (param, short) {
     if (short) {
       return (param.type && param.type.type == Syntax.OptionalType) ?
         '[' + param.name + ']' : param.name;
     }
     return param.name + ': ' + formatters.type(param.type).replace(/\n/g, '');
-  }
+  };
 
   /**
    * Convert a remark AST to a string of HTML, rerouting links as necessary
@@ -87,7 +87,7 @@ module.exports = function (getHref) {
   formatters.parameters = function (section, short) {
     if (section.params) {
       return '(' + section.params.map(function (param) {
-        return formatParameter(param, short);
+        return formatters.parameter(param, short);
       }).join(', ') + ')';
     }
     return '()';