[Maria-developers] Squash aaed3436 MENT-651 [4/8] ALTER ONLINE TABLE

Sergei, I think all the commits starting from [4/8] ALTER ONLINE TABLE should be squashed. I will also add a better description in the commit message covering our latest discussions. I would also embed a reference to the original unsquashed branch. It seems to me as a good idea in sense of helping the reader investigate the code -- Yours truly, Nikita Malyavin