upgrade: use 'improvement' object for action too This simplify multiple pieces of code. For now we restrict this upgrade to the top level function to keep this patch simple.

upgrade: implement equality for 'improvement' object Through the code, we use a mix of 'improvement' object and string. Having a single type would be simpler. For this we need the object to be comparable.

upgrade: simplify some of the initial dispatch for dry run Since we already have the list of deficiencies, we can use it directly.

upgrade: simplify 'determineactions' Since we only takes 'deficiencies', we can simplify the function and clarify its arguments.