Fixed MPD module bug and updated file names.

* mpd_send_idle_mask() was actually called twice, which caused the
  module to crash (and the CPU to rise dangerously).
* Icons now have the module name as prefix (except the japanese and
  triangle characters).
* Added RAM icon (and updated CPU icon).
* Removed some unnecessary whitespace (due to MPD module addition).
  => yes, I need to make this configurable