Adding new mesh properties reqiure non-const access.

Remove config tree from ctor and add a createUniformInitialCondition method.

implemented move constructor explicitly.

change from pointer to unique_ptr fixes segfault.

Also rename the boundary conditions container and
remove unused BoundaryConditionsConstIterator.

This function is applicable only to Dirichlet boundary
conditions and not to the Neumann.

Remove default searching of the nodes for _all_ boundary conditions.

geometry->geometrical_set, patch->geometry.