Working on Proof-of-concept

Based on my git segments/sums, I can construct a 

poset of modifications (micro-features), and 

study them in isolation. For the whole-picture study I use (modified) xdot with an extension to handle "gitk://" actions, so I can open gitk (restricted to the segment history) by clicking on single nodes:

git-hierarchy contains the "git-graph -x" command to open such a graph.