Adding 2 new flags in kdeskrc to define margin (gap) between icons

 * This space, vertical and horizontal, was hardcoded in the grid code,
   now it has defaults and can be overriden in kdeskrc file.
 * There is a deviation of about 2 pixels on 1280 screen, FIXME commented.
Merge pull request #81 from KanoComputing/icon-padding-focus

Adding 2 new flags in kdeskrc to define margin (gap) between icons