all CHANGE redesign and splitting of the library

Parsing strings and resolution of any kind are
implemented in separate files. Resolution of cases,
which cannot be resolved at the time of being
parsed, rewritten. Other smaller changes.
diff --git a/src/parser/xml.c b/src/parser/xml.c
index 00ef01b..6e31dcb 100644
--- a/src/parser/xml.c
+++ b/src/parser/xml.c
@@ -30,6 +30,7 @@
 #include "../libyang.h"
 #include "../common.h"
 #include "../context.h"
+#include "../resolve.h"
 #include "../xml.h"
 #include "../tree_internal.h"
 
@@ -485,7 +486,7 @@
             name = leaf->value_str;
         }
 
-        leaf->value.ident = find_identityref(node_type->info.ident.ref, name, ns->value);
+        leaf->value.ident = resolve_identityref(node_type->info.ident.ref, name, ns->value);
         if (!leaf->value.ident) {
             if (log) {
                 LOGVAL(DE_INVAL, LOGLINE(xml), leaf->value_str, xml->name);
@@ -510,6 +511,7 @@
         new_unres->is_leafref = 0;
         new_unres->dnode = node;
         new_unres->next = *unres;
+        new_unres->line = LOGLINE(xml);
         *unres = new_unres;
         break;
 
@@ -529,6 +531,7 @@
         new_unres->is_leafref = 1;
         new_unres->dnode = node;
         new_unres->next = *unres;
+        new_unres->line = LOGLINE(xml);
         *unres = new_unres;
         break;
 
@@ -798,7 +801,7 @@
 
         /* resolve path and create a set of possible leafrefs (we need their values) */
         if ((*list)->is_leafref) {
-            if (resolve_path((*list)->dnode, sleaf->type.info.lref.path, &refset)) {
+            if (resolve_path_arg(*list, sleaf->type.info.lref.path, &refset)) {
                 LOGERR(LY_EVALID, "Leafref \"%s\" could not be resolved.", sleaf->type.info.lref.path);
                 goto error;
             }
@@ -820,10 +823,14 @@
 
         /* instance-identifier */
         } else {
-            if ((resolve_instid((*list)->dnode, leaf->value_str, strlen(leaf->value_str), &refset) || refset->next)
-                    && (sleaf->type.info.inst.req > -1)) {
-                LOGERR(LY_EVALID, "Instance-identifier \"%s\" validation fail.", leaf->value_str);
-                goto error;
+            if (resolve_instid(*list, leaf->value_str, strlen(leaf->value_str), &refset)
+                    || (refset && refset->next)) {
+                if (sleaf->type.info.inst.req > -1) {
+                    LOGERR(LY_EVALID, "Instance-identifier \"%s\" validation fail.", leaf->value_str);
+                    goto error;
+                } else {
+                    LOGVRB("Instance-identifier \"%s\" validation fail.", leaf->value_str);
+                }
             }
 
             while (refset) {