Check row count or last log book row before saving

[daniele-athome]

To defend against overwrite of log book rows, put a safety check before creating a row to check:

• if the current row number is still the same
• if the last (end) hour meter value is still the same (not necessarily the new start value; the last end value must be kept some how)
• if the last row timestamp (column A) is still the same from when the modal was opened

When updating or deleting a row, reload the row from the server and verify that the whole model is identical to the one we have.