Fixed some issues in preferences

 * Multiselect and sortable fields did not work
 * Added styling for sort fields
 * Added own module for multiselect
 * Unified some file names
 * Some small cleanups
 * Improved multiselect code

Change-Id: I52d2cf8a5c44d674e566dd1476ff599a6bf497b8
Merge "Fixed some issues in preferences"