Update `locale' functionality.
    
        - When you use filter option, it is required that you specify the
          full name of the file you want to match. If you want to match
          many files that begin with the same name, then the .+ or .*
          should be added to the filter pattern. This is required in order
          to find just one exact files when there are many files that
          begin whith the name of the single file we want to match. For
          example, we want to match the file named `example.svg' in the
          following list:
    
            example.svg
            example-1.svg
            example-2.svg
    
        - Prepare directory structure to receive .po files.