Explicit instantiation of template CUDA reduction.

Adding tnl-view tool.

Adding explicit template instantiation.
Moving some _impl.h files into implementation dir.

Adding directory legacy for old code.

Implementing PDE solvers and time steppers.

Changing explicit solvers - Merson and Euler.

Renaming tnlArray to tnlMultiArray.

Finishing new template interface for GMRES.

so far).

Adding unit tests for tnlString, tnlObject and tnlArrayManager.

Adding new class tnlArrayManager for managing arrays - allocation/deallocation, load and save functions etc.
tnlVector is derived from tnlArrayManager.

Fixing operator == in tnlString.