Fixes/enhancements for iftable_mib.lua
Fixes/enhancements for iftable_mib.lua

  * add new iftypes
  * pass if{Descr,Name,Alias}
  * fix typos
  * use {r,t}xpackets as unicast packets if
    mcast/bcast stats are not available

alexandergall/snabbswitch,Igalia/snabb,snabbco/snabb,SnabbCo/snabbswitch,dpino/snabb,Igalia/snabbswitch,Igalia/snabbswitch,snabbco/snabb,dpino/snabb,eugeneia/snabb,SnabbCo/snabbswitch,dpino/snabb,eugeneia/snabb,snabbco/snabb,Igalia/snabb,eugeneia/snabb,snabbco/snabb,Igalia/snabb,eugeneia/snabbswitch,Igalia/snabb,alexandergall/snabbswitch,Igalia/snabb,Igalia/snabb,snabbco/snabb,eugeneia/snabb,dpino/snabb,Igalia/snabbswitch,Igalia/snabb,alexandergall/snabbswitch,Igalia/snabbswitch,dpino/snabb,dpino/snabb,alexandergall/snabbswitch,SnabbCo/snabbswitch,snabbco/snabb,eugeneia/snabbswitch,dpino/snabbswitch,eugeneia/snabb,snabbco/snabb,eugeneia/snabbswitch,alexandergall/snabbswitch,dpino/snabbswitch,eugeneia/snabb,dpino/snabb,SnabbCo/snabbswitch,dpino/snabbswitch,dpino/snabbswitch,snabbco/snabb,eugeneia/snabbswitch,eugeneia/snabb,alexandergall/snabbswitch,Igalia/snabbswitch,Igalia/snabb,alexandergall/snabbswitch,eugeneia/snabb,alexandergall/snabbswitch