backward_find_char
Description:
Same as forward_find_char, but goes backward from this.
Parameters:
| this | 
           a TextIter  | 
      
| pred | 
           function to be called on each character  | 
      
| limit | 
           search limit, or null for none  | 
      
| user_data | 
           user data for   | 
      
Returns:
| 
           whether a match was found  |