"No valid config file" error message is missing newline

Build the program, run osk-sdl -t and notice how the shell prompt is put on the same line as the error message.

me@my> bin/osk-sdl -t
Could not open config file: /etc/osk.conf
No valid config file specified, use -c [path]me@my>

It seems that the error message is missing a newline character.

fprintf(stderr, "No valid config file specified, use -c [path]");

The newline appears to be present on other error messages such as

fprintf(stderr, "No device path specified, use -d [path] or -t\n");