Add XPath parser for xpath -> lua path
Add XPath parser for xpath -> lua path

This converts an XPath query which would be made against a yang
model and converts it to a lua path. This path can the be used
to easily resolve a node in a data tree.

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