Vectormath

New Features
See 34
- `Vector2` Constructor accepts polar coordinates (with the optional polar keyword argument)
- `Vector2` and `Vector3` instances have `rho`, `theta`, and `theta_deg` as properties
- `Vector3` instances also have `phi` and `theta_phi` as properties

For further discussion on how to generalize some of these changes, especially with regard to dimensionality, see 35

Thank you Evelyn-H!

New Feature
- `angle` method on `Vector2` and `Vector3` to calculate the angle between two vectors. Thank you josephjcontreras! (See: 31 and 32)

Backwards Incompatible Updates
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- Vector operations have been updated to prevent invalid vector states. This means either viewing vector operation outputs as `numpy.ndarray`s if they are the wrong shape (using `__array_wrap__`) or erroring if operations result in invalid vectors (using `__array_finalize__`).

Note: the current implementation still does not always provide desired results; for example, calling `flatten()` on a `Vector3Array` in Python 3 will error, but in Python 2 it will not, creating an invalid-shape `Vector3Array`. Overall, these updates encourage users of `vectormath` to cast their vectors to numpy arrays when performing non-vector operations.

Other Updates
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- `Vector2` now has a `cross` method which evaluates to a `Vector3` with 0 for the x and y components. Thank you Redhotsmasher!

Minor changes
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- Branding updated to Seequent

Minor Changes
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- LICENSE is now distributed with the vectormath package

Minor Changes
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- First release of `vectormath` under ARANZ Geo branding
- Explicit support for Python 3.3 is dropped

Major Features
- Removal of `Matrix`, `Plane`, and `Parallelogram` classes
- These classes were incomplete and need significant polishing before getting used

Minor Changes
- No longer dependent on `future`