Print ASCII2NC warning message about python embedding support not being compiled

[JohnHalleyGotway]

Describe the Enhancement

Running ascii2nc with python embedding without optional python embedding support being compiled results in this error message:

bin/ascii2nc -format python 'scripts/python/read_ascii_point.py data/sample_obs/ascii/sample_ascii_obs.txt' out.nc
...
ERROR  : set_format() -> unsupported ASCII observation format "python".

Whereas, doing the same with plot_data_plane provides a much better error message:

bin/plot_data_plane PYTHON_NUMPY plot.ps 'name="scripts/python/read_ascii_numpy.py data/python/fcst.txt FCST";'
...
ERROR  : Met2dDataFileFactory::new_met_2d_data_file() -> Support for Python has not been compiled!
ERROR  : To run Python scripts, recompile with the --enable-python option.

Recommend enhancing the ascii2nc error message to make it more clear, and consider reviewing other MET tools that process python point observations as well.

Time Estimate

4 hours.

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