tcp-ipv6 used a non-exist method resolve6

New submission from ablmf <None>:

In branches/tcp-ipv6-3014/twisted/internet/tcp.py line 924

{{{
#!python
def resolveAddress(self): 
    """ 
    Lookup the IPv6 address for self.addr[0] if necessary, then set 
    self.realAddress to that IPv6 address. 
    """ 
    if abstract.isIPv6Address(self.addr[0]): 
        self._setRealAddress(self.addr[0]) 
    else: 
        d = self.reactor.resolve6(self.addr[0]) 
        d.addCallbacks(self._setRealAddress, self.failIfNotConnected) 

}}}

But no reactor has a resolve6 method.

This would cause problem when user create a Client6 with a hostname.

----------
Type     : defect
Component: core
Keywords : 
Priority : normal
Nosy     : 
----------
http://twistedmatrix.com/trac/ticket/4120