Merge pull request #7 from kubaszczotka/master

merge kuba's fork master with main master
Added right language choices.
Changed vendord variable from empty to None.
Bugfix on amount.
If there was no amount there was no possibility to change the item
because the function tried to write to DB empty value as decimal number.
Simplified 'paidon' edit.
Changed order for element.
Fixed appending ID to modal box.
Eliminated date's conversion to string. This was causing a problem returning None to modal box.