Allow readers to switch between percent and page numbers for reading progress

Currently BookFusion shows only the percentage read in all versions of the ereader, but some users would also like the ability to display page numbers instead of percent. This means that the page numbers would have to be calculated when first opening the book, then recalculated whenever there are formatting changes made since that will impact the display and potentially the number of pages.

This would probably best be given as an option in a user's settings, to use page numbers or percent for progress, allowing each person to set their own preference.