- Refactored OnCheckDependantDates, to comply w/new date types. We always compare datetime objects: in the case that we have date and time, we construct it directly and in the case that we just have a date, we build an hypothetical time.
 This hypothetical time, is as permissive as possible so we use QTime(0,0,0,0) for start times and QTime(23,59,59,999) for end times (*always* UTC).
- this changed called for adding an extra field on the table structure, to indicate if we have time
- for the sake of simplicity, the formatting on QTimeEdit, was changed to 24 hour ('HH:mm:ss') and so was the time on the preview queries ('HH24:MI:SS')
- CheckDependant dates was put back on all relevant forms
- fixed bug on mapTablesL container, that was wrongly pointing sampled_cell has having *no* date fields;