Freeciv

Some actions are activities. Those aren't done until enough work (stored in a unit's activity_count) has been performed. The work is done at turn change. Other actions are instantaneous. They are performed (or fails) at once the unit is ordered to perform them.

Introduce the constant ACT_TIME_INSTANTANEOUS and the function action_get_act_time(). The constant ACT_TIME_INSTANTANEOUS symbolizes that an action is instantaneous. The function action_get_act_time() returns ACT_TIME_INSTANTANEOUS for instantaneous actions and the amount of work (done at turn change) required to complete it for activities.