Modified TileImages method

Modified TileImages method and the ResizeImage method in the
ImageTileInfo class. Made the changes because the program was getting
out of memory exceptiona on larger image sets (about 100 images, all
3264x2488 cellphone camera pics). Modified the code so that the program
loads the bitmap of the image, resizes it, then saves it, and then calls
.Dispose() on the originalBitmap. The ImageTileInfo list no longer keeps
Bitmaps in memory, it just stores file names. I will probably change the
resize method to a static method at some point as well.