fix page down, page up and del key, added del key to delete function

sfm

@@ -675,15 +675,21 @@ draw() {
 read_key() {
     IFS= read -r -n1 key 2>/dev/null || IFS= read -r key
     if [ "$key" = "$(printf '\033')" ]; then
-        # peek at next char with a very short timeout
         IFS= read -r -n1 -t 0.1 _k2 2>/dev/null || _k2=""
         if [ -z "$_k2" ]; then
-            # nothing followed — bare esc
             printf '\033'; return
         fi
-        # got a second char — read one more for full sequence (e.g. [A [B [C [D)
         IFS= read -r -n1 -t 0.1 _k3 2>/dev/null || _k3=""
-        key="${key}${_k2}${_k3}"
+        # if sequence ends with ~, it may have more chars — read one more
+        case "${_k2}${_k3}" in
+            '['[0-9])
+                IFS= read -r -n1 -t 0.1 _k4 2>/dev/null || _k4=""
+                key="${key}${_k2}${_k3}${_k4}"
+                ;;
+            *)
+                key="${key}${_k2}${_k3}"
+                ;;
+        esac
     fi
     printf '%s' "$key"
 }
@@ -1665,6 +1671,7 @@ while true; do
         G)  SEL=$((COUNT - 1)) ;;
         "$(printf '\033[6~')") SEL=$((SEL + $(term_rows) / 2)) ;;
         "$(printf '\033[5~')") SEL=$((SEL - $(term_rows) / 2)) ;;
+        "$(printf '\033[3~')") do_delete ;;
         "$(printf '\n')"|\
         "$(printf '\r')"|\
         "$(printf '\033[C')"|\