Moved tnlObject_impl.h back to tnlObject.cpp since function definitions
in header files cause duplicates when building libtnl. The constructor
of tnlObject is __cuda_callable__ so it's empty definition was moved
directly to tnlObject.h to make it visible to nvcc.

Problem with marking tnlObject's virtual destructor as __cuda_callable__
is yet to be solved...

Parentheses around operator& are necessary due to operator priority

Used shorter __cuda_callable__ instead of __host__ __device__ and
testing if HAVE_CUDA is defined.

RowLengths was renamed to CompressedRowsLengths.
OpenMP support wads added to matrix-vector multiplication and to scalar
products.
CSR format can use Cusparse for SpMV.

Adding CUDA architecure and CUDA cores to log.

simple-solver and make-project were removed from examples.

Scripts tnl-compile and tnl-link were added.

Min. interations feature was fixed in the GMRES method.
Timers for explicit and semi-implicit timestepping were added.

Parallel reduction in CUDA fixed.
Boundary conditions in linear system assembler fixed.
Min. iterations for linear solvers fixed.