====== Image Cache ======

  * **imageCache.jsp?srcUrl=<URL>** check for a valid cache in **hxmc.imageCache**
  * if nothing exists in **hxmc.imageCache** the image is downloaded to **HXMCSettings.cache_dir**
  * cache is valid as long as **hxmc.imageCache.cacheDate** is less than **HXMCSettings.cache_max_age** days