Recode: fromelement.mode='readonly' new implemented on client, by using CSS...

Recode: fromelement.mode='readonly' new implemented on client, by using CSS attribute 'disabled'. The HTML atrribute 'readonly' is fine for pure 'input' elements, but does not work sufficient for 'select', 'checkbox', 'radio'. Also, the label (left of input) and note (right of input) are now grayed out if set to 'disable'.
FillStoreForm.php, Save.php: strings replaced by constants. New central function getfeMode() used by getJsonFeMode() and getAttributeFeMode()