Tweak to make queries against the redirect table faster as well as a standardization of the module enabled check.

1479420 Replace custom server var detection with request_uri() and only examine the actual path, not params

#1297098 - Change checking of $_GET['q'] in path check function to look for !empty() rather than isset()

Fixed errors in parsing of D7 database array

Removed an errant print_r in the code
Added ability to deny non-existing imagecache URLs to anonymous users (needs lazy session patch, or pressflow to be effective)