Standard CMAKE_CXX_FLAGS are a space-delimited list, but our
CXX_TESTS_FLAGS are manually passed to CUDA_ADD_EXECUTABLE, which
expects a semicolon-delimited list. Blame cmake for such a crazy
language...

- Use math function from TNL/Math.h instead of the standard library
- Many cosmetic changes for readability

- The inherited operator= is weird, but this seems to work.
- Use TNL::pow instead of std::pow etc.

The splitting with if( std::is_same<...> ) is not perfect, the code for
all devices was always visible to the compiler, and irrelevant parts
were optimized out at a much later stage. To fix compilation for MIC and
custom data type, we need proper template specializations.

- Cleaned up unnecessary specializations of TNL::max and TNL::min
- Implemented result type promotion to fix compilation with nvcc
- Added TNL::sqrt, which will be necessary for MIC

It used to work everywhere, but the compilers on CentOS (on penny)
are weird...

Conflicts:
	README

Conflicts:
	CMakeLists.txt
	build
	src/TNL/Assert.h
	src/TNL/Containers/SharedArray.h
	src/TNL/Containers/StaticVector.h
	src/TNL/Containers/StaticVector1D_impl.h
	src/TNL/DevicePointer.h
	src/TNL/Devices/Cuda.h
	src/TNL/Operators/diffusion/LinearDiffusion_impl.h
	src/TNL/Problems/HeatEquationProblem_impl.h
	src/TNL/SharedPointer.h
	src/TNL/Solvers/PDE/ExplicitUpdater.h
	src/TNL/Solvers/SolverMonitor.h
	src/TNL/UniquePointer.h

Conflicts:
	src/UnitTests/Containers/VectorTest.cu