Rename functions, types, etc. Mainly using...
 * 's/SAU_([a-z])/sau_\1/g'
 * 's/SAU_([A-Z][a-z])/sau\1/g'

Move 'doc/' into 'sau/'.
Add 'sau/README.md'.
Split 'COPYING.LESSER' from 'COPYING',
add these files under 'sau/' too.

Also change my email address,
to my new main email address.

Set saugns version to v0.4-dev.

Updated 2023-03-14 to clean up licensing info,
and use ISC for all files outside 'sau/' while
at it. (All outside libsau is only cli stuff.)

Updated 2024-02-29, 'sau/doc/README.SAU' text.