Drawing a string longer then 255 chars wasnt working.

Drawing a string longer then 255 chars wasnt working.

changes to flatten_string_append(...), probably only brecht is interested.
- It was copying from the old malloc'd buffer but never the fixed buffer - the reason >255 length strings didnt render.
- on first malloc for the FlatString allocate 512 rather then 256 chars since the fixed string is 256 chars.
- if the char was '\0' fs->pos was set to 0, not sure why since char cant be '\0' because of the loop that calls flatten_string_append, removed.