Remove 1.0, 1.1 and similar subdirectories
At some point I started creating a 2.0 version of the code, and then found bugs in 1.1 and kept copying bugfixes from 1.1 to 2.0. Then I just gave up and manually merged the work from 2.0 back into 1.1.
The problem is that we are using these directories for version control. This does not make any sense. We should use git for version control (e.g. with a new branch for new features being developed). Then we should delete 1.0 and keep only 1.1 in the toplevel.
This is easy to do (the hardest thing would be to search-and-replace stuff in our guides).
We should do this soon (unless we have a good reason to keep the current scheme).