Fix a single space
Avoid atoi, use std::stoi(), etc.

This is closer to the C++ standard and also avoids some casts.
Merge pull request #20 from vog/improve-casts

Use explicit types of casts
Merge pull request #21 from vog/avoid-atoi

Avoid atoi, use std::stoi(), etc.
Merge pull request #22 from vog/fix-space

Fix a single space
Convert a forgotten cast