screen: display byte value 0x0A in the right places as ^@ or as ^J
In path names and file names, 0x0A means an embedded newline and
should be shown as ^J, but in anything related to the file's data,
0x0A is an encoded NUL and should be displayed as ^@.
So... switch mode at the two main entry points into the "file system"
(reading in a file, and writing out a file), and also when drawing the
titlebar. Switch back to the default mode in the main loop.
This fixes https://savannah.gnu.org/bugs/?49893.
7 files changed