Outstanding items before release

[dmjio]

• [x] randn, randu, etc. should use a list for dimensions
• [x] Tests for file IO, reading / writing matrices
• [x] Add more tests
• [x] Add links to array fire things
• [x] AFConvMode, etc. needs to be wrapped
• [x] Features API needs to be fixed
• [x] AFConvMode, double check to/from is correct.
• [x] Constrain Util functions by AFType
• [ ] Add a Bits instance?
• [x] Doctest on Darwin doesn't work since it forgets about being linked against arrayfire (cannot find .so errors abound)