Restored the rule generator bits from udev-171

Initial commit, no files modified except for build system stuffs, nothing tested yet
Added missing flag in ./configure

Rule-generator installation is disabled by default, this change occurred around udev-174
Added rule_generator/Makefile to AC_OUTPUT list
Fixed syntax errors in rule_generator/Makefile.am
Fixed install target for rule_generator helper scripts
Removed hard-coded paths in rule-writer scripts

Both scripts had hard-coded paths to 'rule_generator.functions'; these were changed
to be substituted in by configure so the paths will match where files are
installed.øy
Initial forward-port of rules.d inotify support