project task - use date not datetime

[Ferdinand]

Hello!
the task work should be recorded based on a "date" (not datetime) field
please see fix/workaround in
http://bazaar.launchpad.net/~camptocamp/c2c-rd-addons/7.0/view/head:/c2c_project_timesheet/timesheet_task.py
date_date field

especially importing time sheets with date only (no time) records all records for the wrong day for all TZ east of UTC

reason: company reporting is impossible if timezone are used
user A in timezone MEZ sees other data and sums then user B in other time zone

even user A sees other sums using group by date (which uses UTC)
all data entered between 0 and 1 AM in winter and 0 and 2AM in summer are grouped in the previous day AND in previous month for the first 1 or 2 hours f the first day of month.
not suitable for accounting (invoicing)

please see also
https://bugs.launchpad.net/openobject-server/+bug/1155843