yin parser CHANGE unify structures for restriction information

must, length, pattern etc statement fits to the same structure so use
only one structure (and connected functions) for all these data.
diff --git a/src/printer/yang.c b/src/printer/yang.c
index 24e5c9d..e66138a 100644
--- a/src/printer/yang.c
+++ b/src/printer/yang.c
@@ -102,19 +102,19 @@
 }
 
 static void
-yang_print_restr(FILE *f, int level, struct ly_must *must)
+yang_print_restr(FILE *f, int level, struct ly_restr *restr)
 {
-    if (must->dsc != NULL) {
-        yang_print_text(f, level, "description", must->dsc);
+    if (restr->dsc != NULL) {
+        yang_print_text(f, level, "description", restr->dsc);
     }
-    if (must->ref != NULL) {
-        yang_print_text(f, level, "reference", must->ref);
+    if (restr->ref != NULL) {
+        yang_print_text(f, level, "reference", restr->ref);
     }
-    if (must->eapptag != NULL) {
-        fprintf(f, "%*serror-app-tag \"%s\";\n", LEVEL, INDENT, must->eapptag);
+    if (restr->eapptag != NULL) {
+        fprintf(f, "%*serror-app-tag \"%s\";\n", LEVEL, INDENT, restr->eapptag);
     }
-    if (must->emsg != NULL) {
-        yang_print_text(f, level, "error-message", must->emsg);
+    if (restr->emsg != NULL) {
+        yang_print_text(f, level, "error-message", restr->emsg);
     }
 }
 
@@ -133,7 +133,7 @@
     case LY_TYPE_BINARY:
         if (type->info.binary.length != NULL) {
             fprintf(f, "%*slength \"%s\" {\n", LEVEL, INDENT, type->info.binary.length->expr);
-            yang_print_restr(f, level + 1, (struct ly_must *)type->info.binary.length);
+            yang_print_restr(f, level + 1, type->info.binary.length);
             fprintf(f, "%*s}\n", LEVEL, INDENT);
         }
         break;
@@ -205,9 +205,9 @@
 }
 
 static void
-yang_print_must(FILE *f, int level, struct ly_must *must)
+yang_print_must(FILE *f, int level, struct ly_restr *must)
 {
-    fprintf(f, "%*smust \"%s\" {\n", LEVEL, INDENT, must->cond);
+    fprintf(f, "%*smust \"%s\" {\n", LEVEL, INDENT, must->expr);
     yang_print_restr(f, level + 1, must);
     fprintf(f, "%*s}\n", LEVEL, INDENT);
 }