Support remaining strain gauge configurations

[adamreeve]

Fixes #267

[codecov-commenter]

Codecov Report

Merging #268 (18ced8e) into master (9ad82c8) will increase coverage by 0.04%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #268      +/-   ##
==========================================
+ Coverage   97.04%   97.08%   +0.04%     
==========================================
  Files          19       19              
  Lines        2503     2540      +37     
==========================================
+ Hits         2429     2466      +37     
  Misses         74       74              

Impacted Files	Coverage Δ
nptdms/scaling.py	97.63% <100.00%> (+0.25%)	⬆️

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