* Update to OpenVR 1.0.10
* Typo fix
* Missing doc comment
* Delete dead examples, cleanup
* Delete dead code
* Remove lifetimes from subsystems
OpenVR must be shut down manually, which invalidates outstanding
subsystem handles regardless of lifetimes, rendering the ergonomic
sacrifice pointless.
Future work: make shutdown safe by inserting checks before every
OpenVR call.
* Depend on our own openvr-sys
* Update metadata
* Update readme
* More detailed safety notes
* Depend on released openvr-sys