added todo and virtual function in tracker base class
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 'master' of https://github.com/opentrack/opentrack into feature/tracker_hotkeys

Conflicts:
	TODO.txt
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
stupid git being a pain, I don't want this change to appear in lib-ovr branch
bump version
Merge libovr 0.2.5 changes!

- mm0zct & sthalik