Update examples to show how to use the post-rewrite barcode reading functions

[jasper-tms]

The current examples are nice, short, sweet examples of how to read barcodes from a vector of values (example01) and from an image file (example02). However example01 currently uses parser.read_barcode (which calls parser.parse_linescan) and example02 currently uses scanner.scan_image_y (which calls parser.read_barcode which calls parser.parse_linescan), and it seems like parser.parse_linescan has fallen out of use after the repo rewrite, in favor of linescan.scan. linescan.scan returns a Barcode object (which has nice features like a .center attribute that returns the center coordinate, among other things) which is preferable to what parser.parse_linescan returns. Let's update the examples to show how to use linescan.scan on a vector of values or an image file.