Bounds-checks and blocksize corrections were applied to user-input,
but constants in the server were trusted implicitly. If these values
did not actually meet the requirements, the user could not set change
a variable, then set it back to the (wonky) factory default or maximum
by explicitly specifying it (SET <var>=<value> vs SET <var>=DEFAULT).

Now checks also apply to the server's presets. Wonky values and maxima
get corrected at startup. Consequently all non-offsetted values the user
sees are valid, and users can set the variable to that exact value if
they so desire.