DOC: Add one line docs summary
Merge pull request #2081 from jseabold/docs-fix

DOC: Add one line docs summary
MAINT: Remove redundant rsync flags
Merge pull request #2082 from jseabold/cleanup-rsync

MAINT: Remove redundant rsync flags
TST: Test missing failure with formula.
BUG: combined can be empty if patsy handles missing. Closes #2083.
TST: Test that missing, formula, and extra arrays work.
ENH: Ensure extra arrays are attached as ndarrays.
BUG: Check input array lengths after missing data handling.
TST: Test that missing, formula, and extra arrays work.
BUG: Check input array lengths after missing handling.
TST: Test for extra arrays with missing and formula
BUG: Handle 2d extra arrays and endog/exog with formula and missing.
TST: Update for dimension handling higher up.
ENH: Ensure ndarray-like is passed up. Needs refactor.
Merge pull request #2084 from jseabold/fix-2083

BUG: Correct issue if patsy handles missing. Closes #2083.
ENH: Make PCA a class and add features

Encompasses all sandbox PCA routines and added features for plotting, selecting
the number of components and rapidly re-projecting on a subset of factors