Reformat and merge documentation for some NSE modules: comm, datafiles, dns,

http, ipOps, listop, and match. This is mainly merging the best documentation
from the module source and scripting.xml into the module, with the aim of
making the source code the canonical source for module documentation.

nselib/comm.lua

@@ -1,52 +1,23 @@
---- The comm module provides functions for common network discovery tasks.
--- Banner-grabbing and making a quick exchange of data are some of
--- these tasks. These
--- functions' return values are setup for use with exception handling
--- via nmap.new_try().\n
--- \n
--- These functions can all be passed a table of options, but it's not
--- required. The relevant indexes for this table are bytes, lines, proto
--- and timeout. bytes is used to provide the minimum number of bytes required
--- for a read. lines does the same, but for the minimum number of lines.
--- proto is used to set the protocol to communicate with, defaulting to
--- "tcp" if not provided. timeout is used to set the socket timeout (see
--- the socket function set_timeout() for details). 
+--- Common communication functions for network discovery tasks like
+-- banner grabbing and data exchange.
+-- \n\n
+-- The functions in this module return values appropriate for use with
+-- exception handling via nmap.new_try().
+-- \n\n
+-- These functions may be passed a table of options, but it's not
+-- required. The keys for the options table are "bytes", "lines",
+-- "proto", and "timeout". "bytes" sets a minimum number of bytes to
+-- read. "lines" does the same for lines. "proto" sets the protocol to
+-- communicate with, defaulting to "tcp" if not provided. "timeout" sets
+-- the socket timeout (see the socket function set_timeout() for
+-- details). 
+-- \n\n
+-- If both "bytes" and "lines" are provided, "lines" takes precedence.
+-- If neither are given, the functions read as many bytes as possible.
 -- @author Kris Katterjohn 04/2008
 
 module(... or "comm", package.seeall)
 
---
---
--- The Functions:
---
---   get_banner(host, port, [opts])
---   exchange(host, port, data, [opts])
---
--- get_banner() does just what it sounds like it does: connects to the
--- host, reads whatever it gives us, and then returns it.
---
--- exchange() connects to the host, sends the requested data, reads
--- whatever it gives us, and then returns it.
---
--- Both of these functions return multiple values so that they can be
--- used with exception handling via nmap.new_try().  The second value
--- they return is either the response from the host, or the error message
--- from one of the previous calls (connect, send, receive*).
---
--- These functions can be passed a table of options with the following keys:
---
---   bytes: Specifies the minimum amount of bytes are to be read from the host
---   lines: Specifies the minimum amount of lines are to be read from the host
---   proto: Specifies the protocol to be used with the connect() call
---   timeout: Sets the socket's timeout with nmap.set_timeout()
---
--- If neither lines nor bytes are specified, the calls attempt to read as many
--- bytes as possible.  If only bytes is specified, then it only tries to read
--- that many bytes.  Likewise, it only lines if specified, then it only tries
--- to read that many lines.  If they're both specified, the lines value is used.
---
-------
-
 -- Makes sure that opts exists and the default proto is there
 local initopts = function(opts)
 	if not opts then