NXinquirefile should return fully qualified path

[Tobias Richter]

As finding an externally linked file involves some heuristics it would be useful if the API command that would be able to resolve any ambiguity would actually do that. Also HDF5 will do that by default, so rather than stripping useful information there, it would be better to be more definitive in the reply on other backends.

[Tobias Richter]

In [1741]:

refs #290, #299

Create link in the right place. The test creates it in the root
and that is where it always ended up by accident anyway.

fixes inquirefile tests on c
No idea what is going on in the C++ world. Should be simpler there, but not for me.

[Freddie Akeroyd]

In [1742]:

Fix path length bug in C++ inquire file command - tests now work. Refs #299