Array methods

[dfellis]

The remaining array methods depend on generic functions and interfaces being implemented, for the most part. (The implementation could be done and tested without it, but it would require declaring a binding for each sub-type for the array, which isn't usable for user-defined types.) The "Vec" types should also be converted to the Array type at this time, including the parallel map functionality. Since Arrays are just Rust Vectors under the hood, this may not require any actual changes to the bound code.

The functions desired for a first v0.2.0 are:

• [x] map
• [ ] filter
• [ ] reduce
• [ ] each
• [ ] find
• [x] join
• [ ] every
• [ ] some
• [ ] delete
• [ ] set (maybe done inside of the automatic type generation)
• [ ] concat
• [ ] repeat
• [x] len
• [ ] has