Merge from Dependencies branch (nmap-exp/patrick/dependencies)

with modifications from [2].

** Short description from [1] **

I have created a patch to NSE that replaces runlevels with a table of
dependencies that clearly outlines what other scripts the script
depends on. The table is of the form:

dependences = {"script1", script2", ...}

Runlevels become an internal representation of the order of scripts
that are generated by the dependencies. Dependencies only enforce
an execution order and not a requirement for execution.

[1] http://seclists.org/nmap-dev/2009/q4/295
[2] http://seclists.org/nmap-dev/2009/q4/446

scripts/smb-check-vulns.nse

@@ -79,9 +79,15 @@ author = "Ron Bowes"
 copyright = "Ron Bowes"
 license = "Same as Nmap--See http://nmap.org/book/man-legal.html"
 categories = {"intrusive","exploit","dos","vuln"}
--- Set the runlevel to >2 so this runs last (so if it DOES crash something, it doesn't
--- till other scans have had a chance to run)
-runlevel = 2
+-- run after all smb-* scripts (so if it DOES crash something, it doesn't till
+-- other scans have had a chance to run)
+dependencies = {
+  "smb-brute", smb-enum-sessions", "smb-security-mode", 
+  "smb-check-vulns", "smb-enum-shares", "smb-server-stats",
+  "smb-enum-domains", "smb-enum-users", "smb-system-info",
+  "smb-enum-groups", "smb-os-discovery", "smb-enum-processes",
+  "smb-psexec",
+};
 
 require 'msrpc'
 require 'smb'