Add getters to the library

Writing from another programming language (Perl in my case), it's a bit of a help to have a getter so that the parameters set can be extracted again from the object. I added these getter functions for my library, I am issuing a pull request because I think they are useful for other programmers writing against the library too. This also alters the structure of liq_attr to add a field speed since it was a lot of work to extract it back again from the other parameters.

If you agree to this pull request I'll also add documentation.