#31 Page number handling of multiple bitmaps to decode is easy to misuse

Advantages: - crossplatform - easy to code and maintain, at least in this simple form (different code needed for each OS in directory-based solution) Disadvantages: - Have to ensure -i arg is scanned.bmp, files are named (inflexible) scanned_0001.bmp through scanned_0044.bmp, and that correct number of pages is passed in. Particularly a problem for scanned images that don't use the same numbering scheme. - If using a directory arg alone, could potentially decode several encoded files by placing them in the same directory (e.g. encoded PaperBack.ini and LICENSE at the same time). Similar advantages if we made changes to allow input to be handled this way as well.