Functions should be bound to context or not use this

[Yomguithereal]

Hello @acarl005. The fact that your functions need this to function has this somewhat uncomfortable side-effect that you cannot use them without calling them from the generatorics object.

Here is what I mean:

// If you do the following for instance:
var combination = require('generatorics').combination;

// This will throw & fail because the function does not have the required scope
combination([1, 2, 3], 2);

A solution would be to bind your function to the correct scope before exporting or rewrite the code marginally not to rely on the scope of the generatorics object.

[Yomguithereal]

On a side note, decomposing functions further would also mean someone could import only parts of the library as a result:

var combination = require('generatorics/combination');

I'll be happy to draft a PR if you want.

[acarl005]

@Yomguithereal Thanks for the feedback! You're absolutely right. I've always found it annoying when I have to manually re-bind methods to their context. The API could certainly be better. A PR would be greatly appreciated!