minimum viable walltaker client based on skalibs.
(mr skarnet if u see this i am sorry for using your nice systems programming library to make goonware)

simple usage ($ID is your walltaker link id):
```
while true; do
	mvwt $ID
	sleep 10
done
```
the cachedir can be set with the -c flag;
the default cachedir is /tmp/mvwt (changeable in config.h)
the cachedir must already exist, so mkdir it if it doesn't exist already.

build time dependency:
	a build of skalibs (if you want static compilation, modify the makefile as per the comments)
runtime dependencies:
	s6-networking (this program uses ucspi for network communication)
	hsetroot (used to actually set the wallpaper)
	
pdjson.{c,h} is a bundled public domain cjson parser available from here: https://github.com/skeeto/pdjson

you might want to remove the `current` file in the cachedir before every
time you start using mvwt;
if the file already exists and your wallpaper is still the same as it
was before, it won't be set again.
(this is because mvwt doesn't have any constant internal state,
it's meant to be run in a cron job or a shell loop and reads `current`
and compares it to walltaker's API response
to check if it needs to download and change the wallpaper)

mvwtc and mvwtimg shouldn't be used directly. they expect to be on
a ucspi connection and are spawned by mvwt.

public domain i guess. do whatever you want with this