Added 'fixed' class to Magellan when in fixed position state

The idea behind this is that you can style the Magellan element
differently when it is fixed as opposed to in its normal state.

The 'fixed' class is already declared by Foundation but I have found no
issues when using it in this instance.
Merge pull request #2547 from damirkotoric/magellan-classes

Added 'fixed' class to Magellan when in fixed position state