Improve node functions

[martukas]

Continuation of #36

• there are probably redundant error checks here
• Parameters could be simplified in light of how our wrapper is designed
• should consider using member functions, as valid node is required for all of them anyways

[eugenwintersberger]

Could you be a bit more explicit here? Which methods do you propose?

[martukas]

For link creation functions, it would be most intuitive to do

base.create_link("where/new/link/goes", target, lcpl, lapl);
base.create_external_link("where/other/link/goes", target_file, target_path, lcpl, lapl);

This is better, because by creating a link you are modifying the base group, the same object via which you would access its links. With free-floating functions, it is less obvious. Does the target come before the link location? Is it the other way around? Instead of having to go read docs, it should be intuitive.

Similarly, for removing

base.remove("path/of/node/to/be/removed", lapl);

For move and copy, it is less obvious, but it could be

base.copy_here("some/new/path", other_node, ocpl, lcpl);
base.move_here("other/new/path", other_node, lcpl, lapl);

[martukas]

@eugenwintersberger any thoughts on this? Would it be ok to implement these?

[eugenwintersberger]

After some meditation ... and despite the fact that I still do not like the idea to implement this as member functions.

For the link functions I suggest the following signatures

void Group::create_link(const hdf5::Path &link_path,
                        const hdf5::Path &target_path,
                        const hdf5::property::LinkCreationList &lcpl,
                        const hdf5::property::LinkAccessList &lapl);
void Group::create_external_link(const hdf5::Path &link_path,
                                 const boost::filesystem::path &target_file,
                                 const hdf5::Path &target_path,
                                 const hdf5::property::LinkCreationList &lcpl,
                                 const hdf5::property::LinkAccessList &lapl);

where link_path is either relative to the base group or an absolute path.

Remove, copy and move looks good for me. Go ahead.