Progress

addrs es un array con direccions => kmalloc solamente
image es un puntero dentro de header => no liberar
header
- reservar con memalign y hacerla executable
- guardarla en estructura principal
- liberara al final
Fix runnable code
Split lib iface on compile/run use cases

In order to compile the filter once to run it over all packets
we need to support compile/run APIs in .so
Handle skb->len and skb->data_len
Handle empty filters in an uniform way

One empty filter translates to '1,6 0 0 65535' so code doesn't need to
handle empty filters really.