Gets or sets a String value at a given offset that will be terminated with 0 character.
Note that for example UTF8 strings might be more bytes than characters, so always use LenB to figure out how many bytes the string occupied and add one to that for the 0 termination.
Information on encoding is not preserved, so if your working with UTF8 strings then you need to restore the encoding type by manually defining it by using DefineEncoding on the receiver side.