In a ChangeHosts request, display 4-byte Internet addresses as IPv4

In a ChangeHosts request, display 4-byte Internet addresses as IPv4
addresses.

When showing a list of keysyms, build the text representation of the
item for the list by appending keysyms to the text of the item as
dissected; this fixes a bug in the display of those keysums, and means
that we don't build a text string with the keysyms if we're not
generating the text representation.

git-svn-id: http://anonsvn.wireshark.org/wireshark/trunk@5179 f5534014-38df-0310-8fa8-9805f1628bb7