Syslinux - May 2012 - Windows Server 2008R2 WDS workaround and pxechn.c32 status

As some have noticed, WDS (Windows Deployment Services) on Windows
Server 2008R2 can't normally be chained with pxechain.com.  Some have
also noticed wdsnbp.com doing something resembling another round of
DHCP (discover/ack/request/offer).  Working on pxechn.c32 I've found
the "issue" and incorporated a workaround into pxechn.c32.  wdsnbp.com
issues a DHCP discover to the IP address listed in packet #2's siaddr
field.  This normally is set to the fist boot server if no full PXE
response is received (in which case the boot server is in packet #3).
When performing a PXE restart (as with pxechain.com), normally only
packet #3 is altered.  This results in wdsnbp.com asking the wrong
server for information.

pxechn.c32 can set any DHCP option with the input as an integer parsed
by strto*(), hex bytes or a character string.  It also has a wait
option and 3 options to make adjusting the PXELINUX DHCP options
easier.

Currently, it's waiting on a function set not currently present in the
tree and final review.

-- 
-Gene