Fix build
api cleanup
Update to libovr 0.2.5, fix crash when no device attached.

Signed-off-by: Stanislaw Halik <sthalik@misaki.pl>
In-absence-of: mm0zct
Rift: avoid leaks, reformat
Merge branch 'feature/libovr-0.2.5' of https://github.com/opentrack/opentrack into feature/tracker_hotkeys
fixed Rift tracker for libovr SDK 0.2.5