Add OpennNI 2 driver

[nh2]

I added OpenNI 2 support, which allows using KFusion with the Asus Xtion and other Primesense devices.

I also included a few other fixes and changed the Makefile so that the C++ compiler, include paths etc. can be set from outside the Makefile and don't need to be hardcoded.

My OpenNI error handling is rigorous but verbose. Tell me if you would prefer a macro instead to make calls+checks one-liners.

[nh2]

I've tested this with my Xtion and it works pretty well.

[GerhardR]

Hi,

Thank you for the nice contribution. It is very clean, and I am pretty happy to include it.

I only would like to have a different integration into the build system. We try to use the CMake file as the real build system. The make file is just there for my own quick hacking and I would like to just keep it in the short form it is now.

Would you mind updating your pull request with an updated CMakeLists.txt file to build your driver?

cheers, Gerhard

[nh2]

Yes, but it will take a while since I first have to finish some other 3D scanning stuff :)

[GerhardR]

No worries, I am also too busy right now. If I get some time, I will pull in your code commits individually.