libqqwing: add getters for puzzle and solution

For GNOME Sudoku, we want to be able to access these integers without
printing them to stdout. First I thought it'd be best to change the
print functions to be more flexible, but I think this is a much better
and simpler approach.
Use better libtool versioning comment

Looking at gnome-online-accounts, I found much better instructions than
those I had selected before. libtool versioning is confusing enough
already.
Merge pull request #6 from Catanzaro/export

Allow accessing puzzle and solution as array of integers