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-enum-domains.nse

@@ -52,6 +52,7 @@ author = "Ron Bowes"
 copyright = "Ron Bowes"
 license = "Same as Nmap--See http://nmap.org/book/man-legal.html"
 categories = {"discovery","intrusive"}
+dependencies = {"smb-brute"}
 
 require 'msrpc'
 require 'smb'