Support creating new repository type via bindings

[karelklic]

Dear all,

here are libsolv bindings supporting the creation of new repositories.

We store package metadata in a MySql database and we need to do dependency resolution on them. As the system dealing with the packages is in Python, it's useful to fill libsolv data structures from MySql via Python as well, without resorting to C :-)

Run-tested, works well. Please consider accepting the patch.

[mlschroe]

Thanks. I'll merge it but I'm going to change the dependency accessors afterwards, because I don't want to expose the repo's "idarraydata" element. (And the s->requires = repo_addid_dep(s->repo, s->requires, id, 0) interface is really much too low level for the bindings.)

So I'm going to replace it with add_provides/add_requires methods.

I'm not really sure how to make the provides of a solvable available, I could add a XSolvable_provides_get function that reurns a "Dep" array, put then people might think they can do s.provides.push(id), which wont work. So maybe we need to use functions here as well (s.set_provides([...])). Any suggestions?