Purpose
========
Some workers don't have a fixed schedule week after week. They can't have a fixed
calendar. The solution is to use the Planning app.
For those workers, the work entries should be generated based on the planning instead of
the resource calendar.

Specification
=============
On structure type add a radio button with those values:
    Generate Work Entries:
	* On a fix Schedule
	* On planning
If "On planning" is selected, set the default calendar to a "Flexible calendar
7 days 24 hours"

On a planning slot template, add a field for the default work entry type (only visible by
Payroll users). This work entry type is used at work entry generation if
the planning slot was created from a template.

When the work entries have already been generated and a new planning slot is created,
a corresponding work entry should also be created. If the slot is later moved, the
corresponding work entry should also be moved accordingly. Also when a slot is moved, the
work entry type should be removed from the work entry because it no longer makes sense
for the new period. This will force the payroll manager to manually check the work
entry type.

Task 2088149