Revert "smurf: Update WVM corrections"

This reverts commit 515eed7140b891f1a3a0f321c3f07b570fdf5567.

The new fits are puzzling as they more noisy and do not apply a desired shift.
Revert "smurf: Fix typo in slope of WVM correction"

This reverts commit 4f12e742e1a24da017f370e88659e16858628876.

The new fits are puzzling as they more noisy and do not apply a desired shift.
Revert "smurf: Fix sense of WVM pwv correction"

This reverts commit 4c8e9d185549c6b5d56ffbe7f29225e253fc3ac0.

The new fits are puzzling as they more noisy and do not apply a desired shift.
Revert "smurf: Add date-dependent WVM calculation"

This reverts commit 48a7833856b41a3d9bd7769ca611620989b1f0b9.

The new fits are puzzling as they more noisy and do not apply a desired shift.