Obsolete usage of MB in output

[myurkin]

ADDA was using a definition of MB as 2^20 bytes, but it is now considered obsolete, steering toward the SI-based meaning of MB as 10^6 bytes. Not to change the numerical values, the easiest is to change "MB" to "MiB" (mebibyte) in all output. But this cause many warnings in tests that compare the output, so this better need to be done before the release.

Some changes in the manual and wiki pages also need to be done.

[myurkin]

Now I am not so sure about the proper solution. Maybe better to keep MB and change the values (once). Anyway, this should be made before the release.