WPPF Improvements

[psavery]

• Make an advanced option, allowing us to change the parameters to the intensity extraction function
• Always apply masks to binned/simulated polar view 2D images
• Make a way to reset all texture parameters to zero

[saransh13]

• I'll add making the difference plot ranges the same as the azimuthal average range as default. The user can zoom in if they'd like, but the default range should be the azimuthal average

[saransh13]

• Another one is to use units of Angstrom (A) in the WPPF module. For legacy reasons, internally, everything is in units of nm. However, we should expose the numbers in units of A to the user. Relevant parameters where this would show up:

1. Lattice constants
2. S_hkl (anisotropic peak broadening parameters)

[saransh13]

• And finally, since the package here is based on the GSAS convention, instead of displaying X, 'Y, and U values, we can display an equivalent size and microstrain. See below for the conversion. These numbers are much more physically meaningful than what is displayed currently. However, internally we could use the same code.

[psavery]

Comments about the equations above:

1. We use K = 0.91 instead of K = 1
2. We will only use the S on the left, not the one on the right
3. LX maps to material_X, LY maps to material_Y, and GP is material_P.
4. S is Microstrain, the first p is Lorentzian Particle Size, and the second p is Gaussian Particle Size.

[psavery]

Add units in parentheses.