[MERGE] release management checklist maker

[MERGE] release management checklist maker

The Release Manager's Guide is a complicated document that must accurately
describe how to prepare all four possible types of release. This makes it
hard to use as the basis for a checklist: for any given type of release, it
must list some steps in the wrong order, and list some steps that mustn't in
fact be taken at all.

We do have a porting tool that prepares a release checklist from the RMG for
a given release type. This set of changes, largely written by Sawyer++,
modifies that tool so that its output lists only the desired steps.