Merge pull request #67 from Lekensteyn/updates

udev: Use uaccess instead of plugdev (pwr/Solaar#66)
account for devices going out-of-range while active
fix battery display in main window
simplify debian/rules a bit
proper shutdown of receiver listeners
persist and restore device settings
only save the configuration once when Solaar ends
shorter thread name on receiver listener
attach configuration to device settings objects
use debconf to check if the plugdev group is necessary
create the plugdev group in postinst, not config
debconf translation support (just english for now)
document Logitech receiver USB ids
version 0.8.9.4
fixed ubuntu dh_link
gh_pages build script updated
renamed NANO receiver id
K750: register the FN swap setting statically, no need to detect it at runtime
new single-window UI
polling: it may happen that the receiver is removed mid-poll