Fixed annoying error sound when double clicking

 * When kdesk works in "oneclick opens app" mode (OneClick: true flag)
   and if the user double clicks on and icon, the error sound is played.
   This change resolves this annoyance, making kdesk discard those extra clicks
   until "ClickDelay" time flag has expired.
Merge pull request #70 from KanoComputing/2click-sound

Fixed annoying error sound when double clicking