stri_read_lines: maximal supported file size is ~0.67 GB

This function should be rewritten if larger files are to be supported.

stri_write_lines is most likely affected as well

This is due to how these are currently implemented, see #395 for the underlying issue (stri_encode)

Start by examining stri_read_lines and stri_write_lines, then read issue #395 for the underlying stri_encode limitation. Determine how the current implementations impose the approximately 0.67 GB limit and define what larger-file support should cover for both functions. Done means the functions support the agreed larger sizes without the current limitation.

Written by the indexing model from the issue text.