Start on polarization restart.
Merge branch 'master' into optipol
Mostly finished with LinPol and HalfWavePlate.

Need testing and rotate.
Polarimetry draft complete; Added new instruments.vis for OptiPol.
Bug fixing: things at least run now.  OptiPol needs to align things.
image.gcentroid improvement; polarimetry bug fixing.
Merge branch 'master' into optipol

Conflicts:
	mskpy/image/analysis.py
Fix HalfWavePlate crash when uncertainties are provided.
Work on polarimetry.

Combine linear_pol and linear_pol_angle.

Add p_eff.

Add LinPol.table method.
Add rotation uncertainty to LinPol.
Keep track of LinPol rotations.
Reincorporate rotation support into HalfWavePlate.
Bug fix last commit on HalfWavePlate rotation attributes.
LinPol.rotate fix.
Corrected the direction of LinPol.rotation.
Add instrumental polarization corrections to polarimetry.
Removed ds9.
Add polarimetry and config to mskpy docstring.