Remove iniparser, introduce BuxtonList and BuxtonHashmap

Ok so revisiting some of yesterdays commits..
This time we fix cross-linking, kill iniparser (Mike should be happy :P), introduce BuxtonList and BuxtonHashmap

Why BuxtonList? Because it powers BuxtonHashmap.

Why BuxtonHashmap? Its way cleaner. And highly efficient. And easy to see what's going on in there :) Also, it cleans up after itself very efficiently, no indirectly lost memory, which is the big problem we have right now with systemd's hashmap.

We can use BuxtonHashmap in place of the client list cruft. Also, we just gained a new singly linked list as a result of the changes, so can even make use of that if we need to. It's also nice and clean.