EFA#105 Obman-Auswahl berücksichtigt nicht Anzahl Sitze im Boot

[cubitusgh2]

Create session / Late entry

If a boat has more than one seats, the user can define an "Obmann". The dropdown for selecting the "Obmann" always contains all entries for up to 24 seats.

This should be changed so that only valid seats for the boat can be selected, or an invalid selected option for "Obmann" should be checked.