Make all functions static

It's enough to limit the function scope to memo.c as that's the only
source file there is. For now at least.

Signed-off-by: Niko Rosvall <niko@ideabyte.net>
Fix note_status_replace

There was a problem where note_status_replace failed when note id was
more than one char long. Thanks for Mikael Berthe for noticing the bug.

Signed-off-by: Niko Rosvall <niko@ideabyte.net>
Update 1.2 information

Signed-off-by: Niko Rosvall <niko@ideabyte.net>
Fix a typo

Signed-off-by: Niko Rosvall <niko@ideabyte.net>