`Tome.inc` now accepts a NumberTome as argument

# `Tome.inc` now accepts a NumberTome as argument

## Related Issue

https://github.com/Wizcorp/node-tomes/issues/37

## Note

It seems that the current code base on the `master` branch can't run `make lint-all` successfully and so the git hooks for `git-commit` fails.
I guess this should be the subject of another Issue/Pull Request. However, I made sure that `make test` works.