Clarified function names. added every necessary convert function. Lexicon datetext: textual format => 'YEAR-MONTH-DAY HOUR:MINUTE:SECOND' e.g. '2005-11-16 15:11:44' default value: '0000-00-00 00:00:00'

datestruct:

tuple format => see http://docs.python.org/lib/module-time.html
(YEAR, MONTH, DAY, HOUR, MINUTE, SECOND, WEEKDAY, YEARDAY, DAYLIGHT)
e.g. (2005, 11, 16, 15, 11, 44, 2, 320, 0)
default value: (0, 0, 0, 0, 0, 0, 0, 0, 0)

dategui:
    textual format for output => 'DAY MONTH YEAR, HOUR:MINUTE'

e.g. '16 nov 2005, 15:11'
default value: _("N/A")