add reading progress bar at the bottom of ReaderView for pdf/djvu reader
And there is also a toggle full screen option to turn on/off the progress bar.
a better looking progress bar widget
rename footer.lua to readerfooter.lua
Merge pull request #766 from chrox/progress_bar

add reading progress bar at the bottom of ReaderView for pdf/djvu reader
Merge branch 'new_ui_code' of github.com:hwhw/kindlepdfviewer into new_ui_houqp