Add functionality to predict or find SNOs of two platforms

[adybbroe]

This PR adds a script to find Simultaneous Nadir Overpass (SNO) points for two platforms.
It is build around a python script that has been used at SMHI and proved to give reasonable accurate results.
Here we will attempt also to verify its accuracy in finding actual SNOs verified by data r other independent methods. Currently it being compared against an old Fortran program (provided by colleagues at NOAA) and proved to give very reliable SNOs.
At SMHI this has been used to match Calipso lidar products with imager sensors like MODIS, AVHRR and VIIRS. Here we will test it also for matching other platforms.

NB! Be aware that this PR replaces an older PR that got stalled, see #51

• Closes #xxxx
• Tests added
• Tests passed
• Passes flake8 pyorbital
• Fully documented

[codecov]

Codecov Report

Attention: Patch coverage is 87.61062% with 56 lines in your changes missing coverage. Please review.

Project coverage is 87.62%. Comparing base (18340ca) to head (8ee7bf7).
Report is 8 commits behind head on main.

Files	Patch %	Lines
pyorbital/sno_utils.py	89.45%	25 Missing ⚠️
pyorbital/logger.py	0.00%	17 Missing ⚠️
pyorbital/tle_archive.py	77.77%	10 Missing ⚠️
pyorbital/tests/conftest.py	86.20%	4 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #153      +/-   ##
==========================================
+ Coverage   87.51%   87.62%   +0.11%     
==========================================
  Files          14       22       +8     
  Lines        2210     2658     +448     
==========================================
+ Hits         1934     2329     +395     
- Misses        276      329      +53     

Flag	Coverage Δ
unittests	87.62% <87.61%> (+0.11%)	⬆️

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[coveralls]

coverage: 85.632% (-1.9%) from 87.562%
when pulling b87c2f3 on adybbroe:sno-finder
into dbabd00 on pytroll:main.

[coveralls]

coverage: 87.257% (-0.3%) from 87.562%
when pulling cf1e49f on adybbroe:sno-finder
into dbabd00 on pytroll:main.

[coveralls]

coverage: 87.37% (-0.2%) from 87.562%
when pulling 915f366 on adybbroe:sno-finder
into dbabd00 on pytroll:main.

[coveralls]

coverage: 87.585% (+0.02%) from 87.562%
when pulling dc78d11 on adybbroe:sno-finder
into dbabd00 on pytroll:main.

[coveralls]

coverage: 87.717% (+0.2%) from 87.562%
when pulling fe60b58 on adybbroe:sno-finder
into dbabd00 on pytroll:main.

[coveralls]

coverage: 87.584% (+0.02%) from 87.562%
when pulling 330e3cf on adybbroe:sno-finder
into dbabd00 on pytroll:main.

[coveralls]

coverage: 87.603% (+0.04%) from 87.562%
when pulling 8ee7bf7 on adybbroe:sno-finder
into dbabd00 on pytroll:main.