Make calculation of PV row coords vectorized

Now can create PV rows and ground based on vectorized calculations …

* next is calculating shadows...!

Make sure not trying to transform with index out of range

Added test for 2D solar vector calculation

Vectorized ground shadow coords calculation

Updated shadow coords calc, now makes more sense

Order the shadow coords, and calculate when direct shading happens

Leverage numpy indexing for pv row coordinates

Finally able to create ground shadows from vectorization

Can calculate cut points vectorized

Recurse to create ground surfaces with cut points and shadows

Fix calculation of cut point coordinates: needed radians for rotatin

Add missing pieces from other class: interrow shad, neighbrs, views

Started formatting OrderedPVArray to the fit/transform paradigm

Fix class method: all tests in test_pvarray.py pass

Now casting shadows and cutting grnd in transform + private methods …

* fixed tests accordingly

Now all pvarray properties will be rebuilt everytime called …

* because pvrows and ground can change, so it's hard to know
if an update needs to be done or not

Now reflectivities passed to irradiance models at init

New pv array class methods and use private methods as well

Update engine to run pv arrays with new fit/transform paradigm

fix pvarray vfcalculator and models tests

Fix edge point calculation issue and run fn tests …

* the edge pts list was not re-initialized at every interation

Quick fix for projection approximations errors in fast class

Make direct shading condition consistent with previous class

Replace old class with new one: shaded len infinites smaller, reidxd …

* shaded length is somehow infinitesimally smaller than with previous class,
but this has virtually no impact. To be investigated later
* now surfaces have more logical indexing (from left to right, increasing index)
in ground object, so matrices ordering got shifted a bit

Add TODO in test

Start cleaning up

Clean up engine.py docstrings and PVEngine class

Clean up geometry/base.py and udpate docstrings

Updated docstring in pvground.py

Update docstrings of OrderedPVArray

Remove old redundant and slower class

Updated 4/6 tutorials

Implement fix in util function to create ground + add test

Updated tutorials on running timeseries simulations

Update readme and tutorials from sphinx docs section

Clean up and add suggestions

Do not use mutable objects like [] as fn input default values …

* http://effbot.org/zone/default-values.htm