Added common search path for deb packages.

* /usr/include/openni2 is a common install location for unofficial OpenNI2 deb packages.
Removed get[..]Stream() calls and added triggerSingleFrame(..)
Added single-frame triggering.
Merged shutdown(..) with ~OpenNI2Device(..)
Fixed abstraction around existing OpenNI 1.x grabber.

This should help with switching between OpenNI 1.x and 2.x grabbers.
Added fall-through to OpenNI 2 grabber.

If OpenNI 2 is being used, have openni_grabber.h include openni2_grabber.h.
Enabled kinfu CMake option with OpenNI 2.
Disabled some kinfu classes that depend on OpenNI 1.x when OpenNI 2 is being used.
Masked oni_grabber errors when the OpenNI 1.x wrapper is not used.
Added conditional compile instead of changing OniGrabber cast type.

Should prevent regression problems when using OpenNI 1.x.
Split kinfu operator(..) into trackFrame(..) and integrateFrame(..)
Added forcedPose kinfu integration.
Separated out ICP tracking from saving the pose.

* Can check for tracking sanity before integrating the frame data
Made grabber cloud creation public.
Refactored obscure kinfu app function names.

Conflicts:
	gpu/kinfu/tools/kinfu_app.cpp
Fixed confusing names in kinfu app.

Conflicts:
	gpu/kinfu/tools/kinfu_app.cpp