add require global

[mathieudutour]

fix #16

[ccgus]

This patch looks OK, but there's over 127 changes in it, and I bet there only needs to be less than 10.

Looks like there's over 100 changes where whitespace was deleted, can you change those back to what they were previously so there's not as much noise in the patch?

And it looks like for all the new code double spacing was used, where everywhere else uses four spaces for indentation. I can fix that on my end with a copy and paste w/ Xcode's auto-indent easily if you don't beat me to it though.