Add a setting for adding an EOL at EOF and display this character
Depends on !64 (merged), fixes #53 (closed).
This reverts 7e7a4214 regarding the display of the last end-of-line character, and adds a setting (disabled by default, only accessible from GSettings) to automatically add an end-of-line at the end of the file when saving.
This should match what @matt had summarized in #53 (comment 12253).