Add systemd targets

Also autodetect wlans devices
Use wrappers to write to files
Move files around

Use a dispatcher for the udev rule rather than calling the right program
immediatly
mv udev to rules.d

Also mv powersave.config to factory since it will be part of the package
lib
Begin rewrite of Makefile
etc: move files to their correct directories

Also preenable services files for systemd
Rewrite makefile
Makefile: more cleaned up (and working!) uninstall
Makefile: factorize install patterns and munge files
Makefile: correct munge
Add doc
Introduce hooks
bin/powersave: complete rewrite

Merge with factory/powersave.config
Ajust Makefile
powersave: split into small functions
Continue splitting subfunctions

Also introduce the variable $mode which looks at $1 to know if we are on
performance or powersave
Only set variable values if they are not already defined
powersave: add more settings

- disk readahead
- eth wol
- cpu frequency bias
modules: remove btusb by default
powersave: start saving init state

+ bugfixes