Don't add unused columns to list
Fix incorrect member variable name
Add __getitem__ to TableColumns and raise proper exceptions
Remove retdict from cpymad.model.Model
Merge branch 'simplify-gettable' into active-sequence
Fix missing 'self.' in Madx.survey
Remember started state in cern.cpymad.libmadx

This improves "Enable sharing connections to remote process" (15f7a8a).
Fix error: survey has no table summary
Merge branch 'active-sequence' into isolate-cpymad