This template allows to display a sequence of events for the clients,
tags and screens. Currently, it is hard to display images where the
state of an object is more complex than "here how it was before" and
"here how it is now". With this template, it is possible to have a
timeline of events from the initial states to the final states.
Now, as the line count shows, this isn't small. It is in fact an
enormous template. Worst still, this commit is the first *half* of
it. The second half adds the ability to `print()`, display
inline code and support mouse and keyboard events. The code also isn't
world class. Maintaining this template might be non-trivial in the
long run. I am fully aware of those issues. On the other hand, there
is ~100 places where this will be used once the entire
"new rule library" project is completed. This will bring the ~1.2k
line of code to ~12 lines per consumer. From that point of view,
it makes a lot more sense to merge this given how useful it is
at explaining changes within the "core objects".
It is also important to keep in mind that there is currently very
little or no documentation (beside the mandatory one-liner summary)
for these concepts. Those are the most important aspects of AwesomeWM
API and they are the least documented. This is just wrong.