Some complex commands (like commands generated by scripts to define key
bindings or the OSD overlay command) contain new lines, which "corrupts"
logging.
Fix this by escaping the parameters C-style. Abuse the JSON writer for
this, which already has code to vaguely produce C-style escapes.
At first I considered stripping the quotes, but then I thought it's
actually a good idea to leave them in, as it makes things clearer.
Follows an idea by avih.
wm4
4b168bcda3