Aggregation pipeline - $min on fields with type string not working

[vdininski]

If you try to do a $min aggregation on a string field in a collection you receive Infinity instead of the actual result. I still haven't tried, but I think that $max would work the same way. The issue is that _.min returns Ifinity when using strings.

[vdininski]

Also $avg returns NaN if there is a document where the field is undefined

[kofrasa]

I have been working on refactoring the aggregation framework into a library of its own. This will make the core of mingo a bit smaller and provide the extra features on demand. Nonetheless I will get some tests going for these issues soon

[kofrasa]

I also welcome pull requests. Just rebase changes to one commit and add the corresponding tests

[kofrasa]

Fixed in release 0.6.3