Move sf_save() to its own file/section
Change years in file headers (and add headers where they are missing)
Start new save system. Re-implement sf_save.sh(). Also add several functions to support new system.

Add sf_tm_timestamp(), sf_file_is_link(), sf_file_type(), sf_file_mode(), sf_file_owner(), sf_file_group(), sf_file_mtime(), sf_file_checksum(), sf_file_size, sf_file_readlink(), sf_file_realpath().
Merge branch 'sf_save' into develop
Re-commit lost modifications of sf_comment() and sf_uncomment()