lwIP 1.3 port update

Hi

I just wanted to give a quick update on my work on the lwIP 1.3 port. 
The following things have been done since last post:

* Cleaned up the CDL: I added a few top level categories to the CDL like 
APIs, Protocols and Interfaces. I also added some more constraints and 
dependencies. I think there is still place for improvements in this 
area. Also, I implemented the last missing bits of the lwIP 
configuration to the CDL, so all in all, pretty much every aspect of 
lwIP should now be configurable through the CDL.

* Cleaned up the implementation of the 'Simple' mode (single-threaded, 
polled). Also tested this mode with SLIP and Ethernet devices. Also 
cleaned up the httpd_simple test which uses the raw TCP API to implement 
a simple HTTP server.

* Started implementing the 'Sequential' mode (multi-threaded). Written a 
new test called httpd_sequential which uses the netconn API to implement 
a simple HTTP server. Tested only with SLIP yet, as the ethernet 
implementation for the sequential mode is not yet fully implemented.

Now, to finish the port there is still quite a bit of work:

* Finish the ethernet implementation for the sequential mode. I was 
wondering if Jonathan Larmour could give me some insight to how he 
implemented this in the eCosPro version, as he stated that there had 
been quite a few changes from the community port. Maybe eCosCentric 
could even contribute to a new updated lwIP 1.3 port?

* We need some documentation. Again, there is a good chunk already done 
in the eCosPro version and I was wondering if we should try to merge 
with that. Alternatively we have to write the documentation from scratch.

* Sort out PPP. In the current port, there is limited support for PPP 
(only usable in 'Simple' mode for now). This is mainly because I use PPP 
in my own project. We can leave it at that or remove it altogether. My 
point is, PPP usage is quite limited in the current state and should 
probably be removed.

* Update to CVS HEAD once again or wait until the 1.3.1 release and 
update then.

* Testing testing testing :)

Best regards,
Simon