Do not allow removing, moving, updating existing blocks

I started from 2.0.x seemed more logical to me.

will test and then provide merge req.

Hey @Mschuddings, thanks for your MR, and sorry for a long time without a reply

It will take me some time to review your code, BTW:
- such changes require new tests;
- coding standards issues need to be fixed;

The proposed feature sounds interesting to me, but I would like to ensure that it will be helpful to others.