WIP: Better matrix support

[zbeekman]

DO NOT MERGE THIS, WIP!

I just wanted to have a place to look at the diff and discuss implementation details while I work on wrapping this up.

Goals:

• [ ] Natively read ragged edge 2D arrays into native array objects when appropriate
  • [ ] Integer kinds
  • [ ] Real kinds
  • [ ] more? (e.g., complex etc.)
• [ ] Query by path and detect native object
• [ ] Write out 2D native arrays as matrices
• [ ] A mechanism for dealing with 3D arrays It's unclear how to implement this best, it may need to be client side in the application.

Thoughts @jacobwilliams & @porteri?