[CMake] Support for Custom LANG in CMAKE (CUDA and general case)

[t m]

> I think the big problem is that this will only work correctly in makefile
> based systems.  So, VS and Xcode will not work with this version of the Cuda
> stuff.
I understand that you would like to avoid merge changes that
potentially are not adopted
to all platforms/IDEs supported by CMake itself. This is topic related
to point 1.

Topic related to point 2. I think cmake provides interface to define
own language, doesn't it? (e.g. Modules/CMakeDetermine*Compiler.cmake)
The missing part is the possibilities to derived dependency
scanner as it is for C/CXX without patching the sources of the CMake.
See the patch from Peter, he just
extend if statements related to the dependency generation about newly
defined LANG. Would be very nice
to have the CMAKE interface to this part.

regards, T. Majchrowski.