Added user selection to vw_idx_inc.php. This makes it possible to view the timesheets of other people besides those of yourself. This feature is not restricted to the admin.

- restricted timesheet_project and timesheets overview to current user only
- stored timesheet project details when status > 0 (is status submitted=1 and approved=2)
- fixed changing of timesheet_status and timesheet_period on 'new timesheet' action
- fixed addedit.php to display the right timesheet status even when status > 0.
- reworked addedit.php to put more code in functions. It uses showproject() or showtimesheetproject() function to print timesheet_project details.

Todo:
- introduce admin mode in which the admin can alter timesheets even when (status>0) and let admin see other peoples timesheet.

Removed code duplication by introducing a timesheets() php function that will be called from every timesheet overview type (status: all=-1, open=0, submitted=2, approved=3).

- Changing status and period of timesheet doesn't create 2 timesheet now. It only creates one timesheet or updates the current timesheet.

Feature added:
- Added a new row timesheet_worked to database for keeping a total of hours worked that timesheet_period.
- Added row timesheet_worked to inteface.

Make delete, changing status and period work. Make status and period fields in addedit.php readonly when the timesheet has been submitted and approved.

TODO:
- delete from vw_idx_*.php files doesn't work.
- changing status and period on new file creates a duplicate record.

TODO:
- deleting
- updating
- admin mode
- adding project hours and total to timesheet