Merge pull request #12 from vantroys/develop

Bug correction of the timer init function
[mbed] Fixes the mbed dev_get.

Will now correctly returns -1 if smews asks for data when none is available
[mbed] Fixes the previous fix ;)
Fixes a bug in init handler calling

GPIP Init handlers where never called
Broadcasts a packet if the dst MAC is not known
Removes static from get_output_handler (gpip)
Fixes bug introduced in d82e7b
Adds a request_packet_ou_call to smews gpip API

This can be used to make a call to the do_packet_out gpip handler
without waiting for a packet to come in. Can be used in timer or init function
Fixes function prototype
Updates useguide for gpip request out
Adds gitignore rules
Fixes forgotten return
Adds an app to handle UDP.

This provides an API for other apps to register callbacks for a given port

Reception functional, still have to implement transmit
Changes prototype of request_packet_out

Now returns a handle to the created connection (useful in some cases)
UDP app functional

It is far from being optimal (and especially concerning buffer copying),
but it works and is completly outside of Smews core.
UDP now uses the in callback return value

This makes a better use of the connections
Adds comments
First version of dhcpclient app
commits ip configuration on ack
Fixes dhcp bug (swap ports when generating request)