Major rework of link detection code.  We now use DHCP
	as part of the link detection which proves to be much more robust,
	and also supports Open System authentication for wireless networks.

	We no longer use external DHCP client programs.  Instead, we use
	our own DHCP client, based on substantially reworked bits of 'dhcpcd'
	which was written by:
		Yoichi Hariguchi <yoichi@fore.com>
		Sergei Viznyuk <sv@phystech.com>
		http://www.phystech.com/download/
	It resides in the "dhcpcd" directory and was refactored into a general
	purpose DHCP client library by me.

	Also misc fixes (CPPFLAGS->AM_CPPFLAGS, move some stuff around),
	move src/backends/NetworkManagerSystem.h -> src/NetworkManagerSystem.h


git-svn-id: http://svn-archive.gnome.org/svn/NetworkManager/trunk@314 4912f4e0-d625-0410-9fb7-b9a5a253dbdc