Cam view seemsto basically work now, minus some cosmetic fixes and
perspective/depth fixes.

Advances #15.

Will later be replaced with -prefix-free.

Advances #18.

Fix registration of DeviceService on the way.

Works around a bug on Android 7 where the copy/paste toolbar prevents action on controls.

Maths borrowed from https://www.w3.org/TR/2016/CR-orientation-event-20160818/ .

This commit makes it ready for merge into master and continuing
development there, because we verified that the map view is completely
unaffected.

Advances #15.

Advances #15.

This fixes issues with late initialisation of the map view and also
guarantees there is an initial view.