Selecting resources in AircraftReservation-Scheduler

[pschuler78]

The user should be able to select the interesting resources and the reservation-scheduler should only display the rows for these interesting resources.
The resource-scheduler should present an "Add resource..." or "+" button for adding/selecting new resources.

At the moment, the server does not support one-round-trip-query for selected multiple resources. May we should implement comma-separated search strings for "OR" logic of aircraft resources or other filterings.

[pschuler78]

Feature implemented on client