Resolve "export to sbml layout creates partial lines for operators"

Closes #645 (closed)

added 5 commits

• cadaee22 - list comparator implemeted
• ffce141c - line comparator implemented
• 5aefb13c - export/import of reaction uses proper line definition for line center
• c5e6a5f5 - comparators are more verbose
• 0a57f6da - export of center line improved

Compare with previous version

unmarked as a Work In Progress

enabled an automatic merge when the pipeline for 0a57f6da succeeds

mentioned in commit a942169d

merged