CheckBox Multi: checkboxes are now builded with uniq html names. This is...

CheckBox Multi: checkboxes are now builded with uniq html names. This is necessary for the client, to assign values correctly to multiple checkboxes during form update by JSON data.
HelperFormElement.php: new prependFormElementIdCheckBoxMulti()
FillStoreForm.php: new collectCheckboxMultiValue(), process() recoded to collect checkBoxMulti values to one element.
AbstractBuildForm.php: checkBoxMulti elements: a) no longer contains an '[]' at the end, b) get individual names