new interfaces code

[tridge at linuxcare.com]

I've put the new interfaces code in the 2.0 branch. Please let me know
if it breaks anything not mentioned below.

Stuff that I know it breaks:

1) samba will now by default use all bcast capable interfaces. It used
   to use just one interface by default. I think the new behaviour is
   better but it may surprise some people.

2) samba will no longer ever guess the netmask/broadcast. If it can't
   ask the kernel for the netmask and the user doesn't supply it on
   the interfaces= line then the interface won't be used. I thought
   about this for a while and think that while we often guessed right
   in the past (using the A/B/C conventions) too many organisations
   use CIDR and subnetting now that it just isn't safe to guess. When
   we guess wrong the result is the well known "why can't I see Samba
   in the network neighborhood?".

in general the new code should provide much greater flexibility and
better defaults. It will now also behave correctly for DHCP clients,
whereas previously you couldn't setup Samba correctly without really
ugly hacks on a DHCP client. 

another case that is now handled correctly is where the sysadmin puts
the hostname as having an IP of 127.0.0.1 in /etc/hosts. RedHat does
this. In this case we used to bind to 127.0.0.1 before which broke
browsing, now we correctly bind to the real interfaces.

The next step is to change nmbd to be able to dynamically add
interfaces on the fly (for example, when a delayed DHCP response comes
in or a vmware interface comes up). I've done most of the code for
that, it just needs some final touches and testing. I'll probably
commit it tomorrow.

I also need to document the changes :)

Cheers, Tridge