Fix that pypower.opf cannot be called with small pypower format

[SimonUlm]

Issue

When calling pypower.opf() directly on data stored as ppc, the function might fail if the ppc has the wrong number of columns (e.g. when converted from a m. file using _m2ppc). This is supposed to be prevented by adding zero columns in opf.py. However, the added number of columns does not match the size of the current ppc format.

Fixed

• Increased number of columns in bus, such that it covers every possible ppc format
• Moved the adding of zero columns to opf_args.py
• Updated numbers of columns to be added

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 75.84%. Comparing base (0d627ba) to head (28a7b2b).

Additional details and impacted files

@@           Coverage Diff            @@
##           develop    #2383   +/-   ##
========================================
  Coverage    75.84%   75.84%           
========================================
  Files          284      284           
  Lines        33690    33686    -4     
========================================
- Hits         25551    25549    -2     
+ Misses        8139     8137    -2     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[SimonUlm]

Hi,
I noticed that some tests were failing. However, the failing tests in test_pandamodels_runpm.py also fail on my local machine on the develop branch. Is this a known issue or is there something I am doing wrong (this is my first MR to this project)?