MultiCamera: Allow up to 4 physical cameras.

git-svn-id: https://valelab.ucsf.edu/svn/micromanager2/trunk@13672 d0ab736e-dc22-4aeb-8dc9-08def0aa14fd
MultiAndorControl: Extend to up to 4 physical cameras.

(Not actually tested.)

git-svn-id: https://valelab.ucsf.edu/svn/micromanager2/trunk@13673 d0ab736e-dc22-4aeb-8dc9-08def0aa14fd