Issue243 less verbose warning for missing sub package

[Didou09]

Improvements

• The warning message is much more concise (1 header, 1 line per subpackage, 1 bottom line)
  => users have the minimum info without pollution
• The error messages are still stored internally in tofu.dsub and accessible to developers, but just not displayed
  => when an optional subpackage import failed, a developer can still why

Example on ITER:

In  [1]: import tofu as tf
/home/ITER/vezined/ToFu_All/tofu/tofu/__init__.py:99: UserWarning:
The following subpackages are not available:
    - tofu.mag
  => see tofu.dsub[<subpackage>] for details on error messages
  warnings.warn(msg)

In  [2]: tf.dsub['mag']
Out [2]: 'pywed not available => no tofu.mag'

Issues

Fixes, in devel, issue #243

[pep8speaks]

Hello @Didou09! Thanks for updating this PR. We checked the lines you've touched for PEP 8 issues, and found:

There are currently no PEP 8 issues detected in this Pull Request. Cheers! 🍻

Comment last updated at 2019-11-21 08:35:48 UTC

[codecov-io]

Codecov Report

Merging #244 into devel will increase coverage by 2.44%.
The diff coverage is 56.41%.

@@            Coverage Diff             @@
##            devel     #244      +/-   ##
==========================================
+ Coverage   41.47%   43.92%   +2.44%     
==========================================
  Files          79       70       -9     
  Lines       23217    21299    -1918     
==========================================
- Hits         9629     9355     -274     
+ Misses      13588    11944    -1644

Impacted Files	Coverage Δ
tofu/imas2tofu/__init__.py	80.95% <100%> (-5.42%)	⬇️
tofu/version.py	100% <100%> (ø)	⬆️
tofu/mag/__init__.py	33.33% <11.76%> (-18.85%)	⬇️
tofu/__init__.py	91.66% <89.47%> (+11.02%)	⬆️
tofu/tests/tests01_geom/tests01_GG.py	94.43% <0%> (-2.42%)	⬇️
tofu/geom/_comp.py	60.08% <0%> (-0.44%)	⬇️
tofu/tests/tests01_geom/tests03_core.py	90.02% <0%> (-0.06%)	⬇️
tofu/data/_core.py	41.04% <0%> (-0.06%)	⬇️
tofu/mag/equimap.py	0% <0%> (ø)	⬆️
... and 18 more

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[Didou09]

Had been closed without being merged the first time...

[lasofivec]

done, sorry for that 🙈