nvcc does not like duplicate arguments, here it failed with
    nvcc fatal   : redefinition of argument 'std'

Implemeting heat equation benchmark.

Conflicts:
	CMakeLists.txt
	src/core/vectors/tnlVector_impl.h
	tests/benchmarks/tnl-cuda-benchmarks.h
	tests/unit-tests/operators/diffusion/CMakeLists.txt