dump2vcd.py: fix random signal order on python26

This patch sets dict_type of the RawConfigParser to
collections.OrderedDict, which is a default setting for python27, but
needs to be set explicitly on python26.

http://docs.python.org/release/2.7/library/configparser.html#ConfigParser.RawConfigParser
dump2vcd.py: allow signals spanning multiple words

Side effect of this change is that signals wider than 32 bits are now
supported too.