[DOC, INFRA] Initial sphinx site

[emdupre]

• Re-organizes existing documentation and converts into plaintext formats for parsing with sphinx and sphinx-gallery.
• Creates an initial sphinx site for displaying these docs.
• Updates setup infrastructure to smooth installation of the library for building documentation locally.

[emdupre]

I hit a number of errors when running the examples scripts as-is:

``` /Users/emdupre/Desktop/ssm/examples/slds.py failed leaving traceback: Traceback (most recent call last): File "/Users/emdupre/Desktop/ssm/examples/slds.py", line 105, in plt.yticks([0, 1, 2], ["$z_{{\\mathrm{{true}}}}$", "$z_{{\\mathrm{{L. EM}}}}$"]) File "/opt/miniconda3/envs/ssm-docs/lib/python3.9/site-packages/matplotlib/pyplot.py", line 1875, in yticks labels = ax.set_yticklabels(labels, minor=minor, **kwargs) File "/opt/miniconda3/envs/ssm-docs/lib/python3.9/site-packages/matplotlib/axes/_base.py", line 73, in wrapper return get_method(self)(*args, **kwargs) File "/opt/miniconda3/envs/ssm-docs/lib/python3.9/site-packages/matplotlib/axis.py", line 1968, in _set_ticklabels return self.set_ticklabels(labels, minor=minor, **kwargs) File "/opt/miniconda3/envs/ssm-docs/lib/python3.9/site-packages/matplotlib/axis.py", line 1890, in set_ticklabels raise ValueError( ValueError: The number of FixedLocator locations (3), usually from a call to set_ticks, does not match the number of ticklabels (2). ``` ``` /Users/emdupre/Desktop/ssm/examples/hsmm.py failed leaving traceback: Traceback (most recent call last): File "/Users/emdupre/Desktop/ssm/examples/hsmm.py", line 33, in hsmm_em_lls = hsmm.fit(y, method="em", num_iters=N_em_iters) File "/Users/emdupre/Desktop/ssm/ssm/util.py", line 111, in wrapper return f(self, datas, inputs=inputs, masks=masks, tags=tags, **kwargs) File "/Users/emdupre/Desktop/ssm/ssm/hmm.py", line 814, in fit self.initialize(datas, inputs=inputs, masks=masks, tags=tags, **kwargs) File "/Users/emdupre/Desktop/ssm/ssm/util.py", line 111, in wrapper return f(self, datas, inputs=inputs, masks=masks, tags=tags, **kwargs) TypeError: initialize() got an unexpected keyword argument 'num_iters' ``` ``` /Users/emdupre/Desktop/ssm/examples/constrained-arhmm.py failed leaving traceback: Traceback (most recent call last): File "/Users/emdupre/Desktop/ssm/examples/constrained-arhmm.py", line 39, in get_ipython().run_line_magic('matplotlib', 'inline') NameError: name 'get_ipython' is not defined ``` ``` /Users/emdupre/Desktop/ssm/examples/lds.py failed leaving traceback: Traceback (most recent call last): File "/Users/emdupre/Desktop/ssm/examples/lds.py", line 55, in _, x, y = true_lds.sample(T) ValueError: not enough values to unpack (expected 3, got 2) ``` ``` /Users/emdupre/Desktop/ssm/examples/hmm.py failed leaving traceback: Traceback (most recent call last): File "/Users/emdupre/Desktop/ssm/examples/hmm.py", line 58, in model.permute(find_permutation(z, model.most_likely_states(y))) File "/Users/emdupre/Desktop/ssm/ssm/util.py", line 36, in find_permutation assert np.all(tmp == np.arange(K1)), "All indices should have been matched!" AssertionError: All indices should have been matched! ```

which is preventing these 5 examples from executing. For the ones that do run, though, It's starting to look more like a docs site !

[emdupre]

I quite like how they denote broken examples, though hopefully we won't see these errors for too much longer :

[emdupre]

This is ready for review / merging ! cc @slinderman @davidzoltowski