[PL] Remove warning: moving a temporary object prevents copy elision.

Quickfix for confusing error messages from ConfigTree

Simplified VecMatAssembler

Clean up global Mat Vec class interface

Remove GlobalSetup

[NL] Apply all Dirichlet BCs at once.

Tag names of secondary variables better checked

Multicomponent ICs/BCs

If it is not available the default case is <values>.

No need to pass the Node and then fetch its id.

Now implemented for UniformIC.

When creating a new MeshProperty the number of components was not passed
further.

Variable and component ids are ints.

Update the constructors, getGlobalIndex(), and meshGetSubsets()
to include the variable_id.

The global component offsets for each variable are
stored in the _variable_component_offset.