r48920: do not convert empty values, otherwise we will get current date or 1970-01-01 instead
r48938: Fix bad logic breaking historylog
r48960: refactored code to always run Nathans fix (before it was only run for ajax requests, not for initial request)
- for grid this is a real fix by correctly expanding names in auto-repeated rows and therefor running widgets beforeSendToClient methods
- for nextmatch is is just a hack looking at get_rows content and converting everything "looking" like a timestamp to a "Y-m-d\TH:i:s\Z" string
backport of Nathan and mine commits r47919, r48102, r48133, r48142, r48163, r48166 using now ISO time strings instead of timestamps for communication between client and server
had to change signature of validate function to get information for autorepeating through
removed entity-encoding of square brackets, as they mess up validiation (havnt found any negative effects so far)
