"Virtual" version 2.4 (and probably 2.6, potentially 2.8)

Hi,

if someone would pay attention, they would have noticed that I just 
pushed a tag version v2.4.0 and updated accordingly the changelog.

Don't be surprised or confused. As I wrote in a previous e-mail, I don't 
plan to release it, but it just shows that the code has evolved compared 
to the latest 2.2.6 version.

Tonight's weekly release [0] will accordingly be released without the 
old CLI (check the changelog for details), and it would be nice if some 
of you could test it making sure that nothing is broken, after this 
rather important change [1]. But check it only tomorrow!

It'll take probably a bit longer but I'm currently removing everything 
related to API 200 / rdiff-backup 2.0.x, and will probably tag it with 
version 2.6 (also unreleased), and then it would again be good to have 
people test that nothing broke in API 201, e.g. against version 2.2.

We could wait until 3.0 is out to test, but I would prefer to go step by 
step and make sure nothing breaks before too many changes are made to 
know where the issue appeared.

Thanks, Eric

[0] https://github.com/rdiff-backup/rdiff-backup/releases/tag/weekly
[1] 32 files changed, 243 insertions(+), 1708 deletions(-)