Namespace udev rules file to avoid conflicts

Makefile.am

 EXTRA_DIST     = README.md COPYING ChangeLog.md
 
 if UDEV
-udev_DATA      = 90-backlight.rules
-EXTRA_DIST    += $(top_srcdir)/90-backlight.rules
+udev_DATA      = 90-light-backlight.rules
+EXTRA_DIST    += $(top_srcdir)/90-light-backlight.rules
 endif
 
 # lintian --profile debian -i -I --show-overrides ../$PKG.changes

README.md

     ./configure --with-udev && make
     sudo make install
 
-This installs the `90-backlight.rules` into `/usr/lib/udev/rules.d/`.
+This installs the `90-light-backlight.rules` into `/usr/lib/udev/rules.d/`.
 If your udev rules are located elsewhere, use `--with-udev=PATH`.
 
 **Note:** make sure that your user is part of the `video` group, otherwise you will not get access to the devices.

debian/light.postinst

 
 # Reset udev rule action back to 'add', it was set to 'change' during
 # dh_auto_configure to make sure they are effective right away.
-sed -i 's/^ACTION=="change"/ACTION=="add"/g' /usr/lib/udev/rules.d/90-backlight.rules
+sed -i 's/^ACTION=="change"/ACTION=="add"/g' /usr/lib/udev/rules.d/90-light-backlight.rules

debian/rules

 	dh_auto_configure -- --with-udev
 	# Change action type of udev rules to make it effective after
 	# installation, they are reset back with the poinst script.
-	sed -i 's/^ACTION=="add"/ACTION=="change"/g' 90-backlight.rules
+	sed -i 's/^ACTION=="add"/ACTION=="change"/g' 90-light-backlight.rules
 
 override_dh_installchangelogs:
 	dh_installchangelogs ChangeLog.md