rewrote _apply_bindings() to support new tmux 3.0 bindings (4)

failed to source the proper modified file, fixes #303

.tmux.conf

@@ -747,7 +747,7 @@ run -b '[ -z "#{window_active}" ] && [ -z "#{version}" ] && tmux set display-tim
 #     '{i = $2 == "-T" ? 4 : 5; gsub(/^[;]$/, "\\\\&", $i); gsub(/^[$"#~]$/, "'"'"'&'"'"'", $i); gsub(/^['"'"']$/, "\"&\"", $i); print}' > "$cfg.in"
 #
 #   # ignore bindings with errors
-#   while ! out=$(tmux source-file "$cfg"); do
+#   while ! out=$(tmux source-file "$cfg.in"); do
 #     line=$(printf "%s" "$out" | cut -d':' -f2)
 #     perl -n -i -e "if ($. != $line) { print }" "$cfg.in"
 #   done