restructure

Signed-off-by: fbt <fbt@fleshless.org>

sub/issue

@@ -1,20 +1,6 @@
 #!/usr/bin/env bash
 
-err() {
-	printf '%s\n' "$*" >&2
-}
-
-msg() {
-	printf '%s\n' "$*"
-}
-
-set_default() {
-	declare -n _vref=$1
-
-	if ! [[ "$_vref" ]]; then
-		_vref=$2
-	fi
-}
+source lib/util
 
 gen_san_string() {
 	declare d