Nmap 5.51

- [Ndiff] Added support for prerule and postrule scripts.
- [NSE] Fixed a bug which caused some NSE scripts to fail due to the absence of the NSE SCRIPT_NAME environment variable when loaded. Michael Pattrick reported the problem.
- [Zenmap] Selecting one of the scan targets in the left pane is supposed to jump to that host in the Nmap Output in the right pane (but it wasn't).
- Fixed an obscure bug in Windows interface matching. If the MAC address of an interface couldn't be retrieved, it might have been used instead of the correct interface.
- [NSE] Fixed portrules in dns-zone-transfer and ftp-proftpd-backdoor that used shortport functions incorrectly and always returned true.
- [Ndiff] Fixed ndiff.dtd to include two elements that can be diffed: status and address.
- [Ndiff] Fixed the ordering of hostscript-related elements in XML output.
- [NSE] Fixed a bug in the nrpe-enum script that would make it run for every port (when it was selected--it isn't by default).
- [NSE] When an NSE script sets a negative socket timeout, it now causes a controlled Lua stack trace instead of a fatal error.
- [Zenmap] Worked around an error that caused the py2app bootstrap executable to be non-universal even when the rest of the application was universal. This prevented the binary .dmg from working on PowerPC.
- [Ndiff] Fixed an output line that wasn't being redirected to a file when all other output was.