Convert ptree manager to use fibers
Convert ptree manager to use fibers

This will eventually allow streaming the parsing of incoming requests,
and streaming the serialization of the output.

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