cleanup the .decodeKludges method and add docs

README.md

@@ -262,7 +262,7 @@ Before the value is returned, the following replacements are made:
 
 ### decodeHeader(header, options)
 
-Uses the encoding (determined by `.encodingFromHeader(header)`) to decode strings from the Buffer properties of the header.
+Uses the encoding (determined by `.encodingFromHeader(header)`) to decode strings from the Buffer properties of the header's Subfields.
 
 * If `.encodingFromHeader` returns `null`, `options.defaultEncoding` is used.
 
@@ -307,6 +307,26 @@ The same returned object may also have one or more of the following properti
 
 * `timezone` — sender's time zone in `+HHmm` or `-HHmm` form (for example, `-0400`) where `+` may be omitted.
 
+### decodeKludges(header, options)
+
+Does a minor part of what `decodeHeader` does: decodes only the kludge lines.
+
+Uses the encoding (determined by `.encodingFromHeader(header)`) to decode strings from the Buffer properties of the header's Subfields. If `.encodingFromHeader` returns `null`, uses `options` or defaults the same way `decodeHeader` does it.
+
+The kludges are decoded only from the following Subfield types:
+
+* `4 / 'MSGID'` — The ID of the message.
+* `5 / 'REPLYID'` — If the message is a reply to some other message, contains the MSGID of that message.
+* `7 / 'PID'` — The PID of the program that generated the message.
+* `2004 / 'TZUTCINFO'` — Time zone information in `+HHmm` or `-HHmm` form (for example, `-0400`) where `+` may be omitted. (Becomes a `TZUTC` kludge.)
+* `2000 / 'FTSKLUDGE'` — other FTS-compliant “kludge” lines.
+
+The other subfields (including `PATH` and `SEEN-BY`) are ignored.
+
+The kludge lines are decoded without the preceding SOH (`Ctrl+A`, `0x01`) code.
+
+The returned value is a string containing all the kludge lines separated by the Unix line endings (`LF`, `'\n'`).
+
 ### decodeMessage(header, options, callback)
 
 Using the given header, reads the text of the corresponding message (calling `.readJDT` in the process). Then uses the encoding (determined by `.encodingFromHeader(header)`) to decode the text of the message. Calls `callback(error, messageText)` when the decoding is finished.

fidonet-jam.js

@@ -498,14 +498,6 @@ JAM.prototype.decodeKludges = function(header, decodeOptions){
 
    for( var i = 0; i < header.Subfields.length; i++ ){
       switch( header.Subfields[i].LoID ){
-         case 0: // OADDRESS
-         break;
-         case 1: // DADDRESS
-         break;
-         case 2: // SENDERNAME
-         break;
-         case 3: // RECEIVERNAME
-         break;
          case 4: // MSGID
             kludges.push(
                'MSGID: ' + header.Subfields[i].Buffer.toString(encoding)
@@ -516,34 +508,16 @@ JAM.prototype.decodeKludges = function(header, decodeOptions){
                'REPLY: ' + header.Subfields[i].Buffer.toString(encoding)
             );
          break;
-         case 6: // SUBJECT
-         break;
          case 7: // PID
             kludges.push(
                'PID: ' + header.Subfields[i].Buffer.toString(encoding)
             );
          break;
-         /*
-         case 8: return 'TRACE'; //break;
-         case 9: return 'ENCLOSEDFILE'; //break;
-         case 10: return 'ENCLOSEDFILEWALIAS'; //break;
-         case 11: return 'ENCLOSEDFREQ'; //break;
-         case 12: return 'ENCLOSEDFILEWCARD'; //break;
-         case 13: return 'ENCLOSEDINDIRECTFILE'; //break;
-         case 1000: return 'EMBINDAT'; //break;
-         */
          case 2000: // FTSKLUDGE
             kludges.push(
                header.Subfields[i].Buffer.toString(encoding)
             );
          break;
-         case 2001: // SEENBY2D
-         break;
-         case 2002: // PATH2D
-         break;
-         /*
-         case 2003: return 'FLAGS'; //break;
-         */
          case 2004: // TZUTCINFO
             kludges.push(
                'TZUTC: ' + header.Subfields[i].Buffer.toString(encoding)