NSEdoc cleanup.

1. The first paragraph of a function's NSEdoc is used as a short
summary. Some of these were very long, so I split off a shorter summary.

2. Use asterisks (*) to denote bulletted lists, not 'o'

3. Wrap lines at 80 columns

4. a couple other spelling and formatting fixes

nselib/vnc.lua

@@ -109,8 +109,8 @@ VNC = {
   end,
 
   --- Performs the VNC handshake and determines
-  -- o The RFB Protocol to use
-  -- o The supported authentication security types
+  -- * The RFB Protocol to use
+  -- * The supported authentication security types
   --
   -- @return status, true on success, false on failure
   -- @return error string containing error message if status is false