Structured representation of text files on disk.
There is a page structure that we do not put into the structure.
As a result the decoder must pass over nulls, the encoder must insert them.
Transforms between UTF8 and Pascal text.
Pascal text is +ASCII, split into 1024 byte pages padded with nulls, with CR line separators.
ASCII 0x10 indicates the next byte is an indentation count + 0x20.