Support for point observations (wind profilers, rawinsondes as point obs)

I eventually wish to see a way of constraining against point observations. This may have to be done with a separate cost function that weighs in how far certain points deviate from the point observations. This would be useful for integrating in data points from wind profilers, surface based observations (METARs, etc.), uninterpolated radar gates, and from rawinsonde data whose horizontal displacement varies throughout the launch.

The issue identifies no files, tests, or entry points. Begin by locating the existing cost-function and observation-handling paths, then clarify how point observations from wind profilers, METARs, radar gates, and rawinsondes should be represented and weighted. Done requires an agreed implementation scope and validation for these point-observation sources.