Redeclaration of 'should_continue' is hidding external variable
main.lua: Add command-line argument for debugging purposes.

  * -dm = Enable developer mode. Enables debug prints and asserts.

  * This sets to true a global variable _G.developer_debug that can be
    used on the rest of snabswitch to enable prints, asserts or other
    things that are not intended for production.

  * Make all other parts of snabswitch where a debug variable was used
    (or should be used) to depend on this one.
Only print the last_size when debug is enabled (./snabbswitch -dm).

 * This code starts triggering on a kernel >= 3.14 (Ubuntu 14.04 uses
   3.13, so this went unnoticed). It causes a lot of flood because it
   triggers constantly.

 * Example of the output from snabswitch when running same_vlan.ports
   with both VMs running Kernel 3.14.23 and running an iperf test
   (MTU 1500) between both VMs:

      size=  2036
      size=  1524
      size=  2036
      size=  1524
      size=  2036
      size=  1524
      [ .... repeated ad-infinitum ]

 * I have bisected the Linux kernel, the commit that causes this print to
   trigger is fb51879dbceab9c40a39018d5322451691909e15 (merged on 3.14)
   https://git.kernel.org/linus/fb51879
NFV config: fix function load

 - pass t.port_id do virtio
 - create filter only if there are actually rules (# is >0)

Signed-off-by: Nikolay Nikolaev <n.nikolaev@virtualopensystems.com>
neutron2snabb: fix filter generation

 - we do not support filters based on remote_group_id, jsut drop those
 - return an empty list when there are no valid rules found

Signed-off-by: Nikolay Nikolaev <n.nikolaev@virtualopensystems.com>
snabbnfv-traffic: apply config on each internal iteration

Before it was 60 seconds - too slow

Signed-off-by: Nikolay Nikolaev <n.nikolaev@virtualopensystems.com>
Merge pull request #325 from virtualopensystems/misc_fixes

Misc fixes
Merge pull request #315 from dpino/fix-should-continue

Redeclaration of 'should_continue' is hidding external variable
Merge pull request #324 from clopez/last_size-check-debug

Add command-line argument for debugging purposes (-dm) and only print the last_size info when debug is enabled
receive checksum offload
transmit checksum offload
the "insert checksum" bits of TXDESC must reflect the current context
precalculate the offload flags together with the context descriptor
check if the packet needs checksum before asking the chip to do it
add offload support for SCTP
test: start sending doctored packets to see if bad checksums are detected and if good ones can be inserted
adapt new selftest to #293 merge
a string value of "nil" is not a valid default anymore
the sink app can call an optional callback(p) before discarding the packet
test: the packet must have 0000 in the relevants checksum fields