Add Fuse.String#split

The native String#split method has several major bugs across all browsers (these are paraphrased from Steven Levithan's article; see http://blog.stevenlevithan.com/archives/cross-browser-split ):

• IE & Safari 2-3 (and Konqueror) ignore RegExp capturing groups (example: 'a_b'.split(/(_)/) should return ["a", "_", "b"], instead, it returns ["a", "b"] in these buggy browsers).

• Firefox ignores non-participating RegExp groups (see http://blog.stevenlevithan.com/archives/npcg-javascript ), and doesn't splice them into the resulting array as undefined

• IE excludes empty values from the resulting array, but only for RegExes (strings work fine)

Steve goes on to implement a cross-browser solution to fix String#split, which I definitely think we could add to Fuse. However, his implementation uses RegExp decompilation (it breaks the separator RegExp down, then rebuilds it with an explicit g flag), which is extremely costly in all browsers.

Fuse.String#replace uses a RegExp's lastIndex property (instead of RegExp decompilation) to fix function replacement, and the code for fixing String#replace in Fuse and Steve's code for fixing String#split are not all that different. I was thinking of applying Steve's code for a Fuse.String#split implementation, but using a much faster lastIndex solution instead of decomp.