Port new Underscore.js 1.4.0 functionality

[russplaysguitar]

See the Underscore.js changelog: http://underscorejs.org/#changelog

[jfrux]

Nice!

[atuttle]

Thought I'd work on this for day 1 of 24PullRequests, but I found that some of it was already done. Here's what I see as possibly still available:

• _.debounce'd functions now return their last updated value, just like _.throttle'd functions do.
• The min and max functions may now be called on very large arrays. (Not sure if this applies)

Have you already completed these / do they not apply?

[russplaysguitar]

Hey Adam!

You're right about most of this issue being done. The main thing I need to do is find time to update the docs.

_.debounce and _.throttle would be great additions. They should probably execute in their own threads...?

Thanks for your interest in the project.

[atuttle]

I see a few //todo's in the code. Are the holes in the docs listed anywhere?

[russplaysguitar]

Nope! The main TODO for docs is to update the doc generator with any new functions and the new version information.