Move CDORemap here and create FAQ for CDORemap version combination issue

Hi @nperez

For some reason, I neglected to move CDORemap() to s2dv. Here is the moving (without any modification.) In addition, @llledo found problem using CDORemap() with specific combination of module versions. Since we've encountered the version problem several times, it may be good to document the cases somewhere. I add it to FAQ.md now, but we can move it to somewhere else if needed. We can talk about it later.

Cheers,
An-Chi