Change / to // (integer division) in several places

[msabramo]

This fixes a bunch of bugs and test failures in Python 3, which uses "true division" for /

[Byron]

Hi Marc,

Please have the keys to my house, and feel right at home - you now have write access to this repository. Therefore, you can merge this pull-request yourself.

Cheers,
Sebastian

[msabramo]

Thanks, @Byron! I'd love for you to still review things even if I merge them. I don't want to mess up your house or the neighborhood!

[Byron]

Thanks for being responsible :) !
Fortunately, a 93% in test coverage means that my pal Travis will do most of the work in detecting new bugs anyway. Of course, he's not perfect, but should flag the most obvious mistakes.

After all these years of me not looking at smmap, I suppose he is better than I am in maintaining quality.

Nonetheless, if the changes are less trivial, I will be inclined to take a thorough look as well.