Some updates

  * Use class member functions instead of create_function calls
  * Configurable object caching of the widget markup
  * Filterable comment number display
  * Add in escaping / sanitization
  * Improve adherence to WordPress style guidelines ( braces, whitespace, etc. )
  * don't use extract
  * Use HTML5 input type “number” on appropriate fields in the config.
  * Fix some translation strings
  * Fix PHP notices