The former has been formally deprecated for a long time and in CUDA 10.0
it is finally properly marked as deprecated, so the compiler can print
warnings.

- There is an RAII wrapper called ScopedInitializer to handle
  finalization due to C++ exceptions and to avoid calls to Finalize in
  all exit branches.
- Fixed signature of MpiCommunicator::Init to match that of MPI_Init.

The std::isnan method can be safely used in host code (if the compiler
is not moron). There is no device code which uses isnan so the
TNL::isNan function is useless.

This reverts commit 0eff2f63.

It has not been implemented in the past decade so it can be safely
assumed that it is useless.

Refactoring: replaced TNL::SharedPointer with std::shared_ptr for the linear solver and preconditioner

The DeviceType capability does not matter because these objects are
never passed to the device and we need to pass "shared_ptr<Derived>" as
"shared_ptr<Base>".

The vector view types have to be passed by value, because pass by
reference does not consider the converting constructors.

It is actually used only in 2 methods and unnecessarily complicates the
interface for all other solvers.

They are disabled and never really worked for these objects...

Works fine with g++ 5.5 and nvcc 8.0 in Arch Linux. File a bug report on
Gitlab if you have problems.