Fix escaping of $CMD of automatic title

Fixes formatting on some rare cases when a percent ends up in the `$CMD` variable, examples below:

- When assigning a variable, $CMD ends up with the second parameter;
in this case, $CMD will contain **+%s%N**, messing with the syntax:

 ```sh
a=`date +%s%N` 
```

- A function (or command in general) that contains a percent symbol:

 ```sh
 to\%() { echo $(( $1 * 100 / $3))\% } # $CMD will equal to "to%()"
 to% 2 of 10 # $CMD will equal to "to%"
```