Implemented module for datatables server-side processing mode.
Major update of baseline functionality.

+ reworked database module to support virtual fields as class properties.
  Card table type and status are now translated into text at the backend.
+ database module now properly looks for primary key in a model fields and shows warning
  if there is no one present. This primary key then being used in delete operation.
  Since recent change in select mechanics required models to have field names identical to those in database,
  delete was broken for some time. This version fixes this bug.
+ Refactored stoppark.js into stoppark-lib.js and stoppark.js.