+ Adds a specification for the new ldap extensible filter

I am not sure about this, since I haven't been able to find
documentation about what this does. This should work, though.

Cleanup of comments and exceptions, adds specification for
Filter.ex and a parser method.

lib/net/ber/ber_parser.rb

@@ -102,7 +102,7 @@ module Net
           n.ber_identifier = id
           n
         else
-          raise BerError.new( "unsupported object type: id=#{id}" )
+          raise BerError, "unsupported object type: id=0x#{id.to_s(16)}"
         end
 
         obj