Add list subcommand

[gdemonet]

The command-line tool defined in #3 should first have sufficient capabilities to extract the list of changelog fragments from Git history.
For this purpose, we want to add a list subcommand, with the following behaviour:

• list --in X.Y.Z would return all fragments included before the X.Y.Z tag but after the most recent tag that comes before it (in terms of Git history)
• list --from A.B.C --to D.E.F would return fragments added after A.B.C and before D.E.F
• list --from X.Y.Z would return fragments added after X.Y.Z up to the current HEAD
• list would return fragments added after the most recent tag

This subcommand would output filenames at first, additional output formats could be added in the future (e.g. showing in which version such file was added, the date of first addition, of last modification, ...)

[NicolasT]

I was looking at implementing this, and it occurred to me we could do this somewhat differently, more alike how git diff etc. work. Basically:

• changelog-binder list is as you describe without options (somewhat like git diff in a tree, diff from last commit to working tree)
• changelog-binder list X.Y.Z would be as-if --from X.Y.Z is used (somewhat like git diff ref1, diff between given ref and working tree)
• changelog-binder list A.B.C...D.E.F would be as-if --from A.B.C --to D.E.F is used (somewhat like git diff ref1...ref2, diff between ref1 and ref2)

The --in variant could be something like changelog-binder list X.Y.Z^...X.Y.Z

Basically, we treat version strings as Git treats commit refs.