Add Dealias Velocity function

[kenkehoe]

We need to add a function to dealias velocity for VPT data.

[AdamTheisen]

Used in the codes for the vertical pointing radars and doing the profile comparisons. This would be to ensure the doppler velocities are unfolded

[AdamTheisen]

@kenkehoe we should check with Py-ART and @scollis on if their dealiasing codes can be used for VPT data.

[zssherman]

@AdamTheisen Should be able to dealias even VPT data with Py-ART.