* Since fontchooser is replaced by selectmenu, it
is no longer needed. So I rewrite it into font.lua
module which can cache faces that shared among all
UIs.
* add progressBar method in graphics.lua to draw
reading progress.
* add reading progress information in reading menu.
It is just a demo. Should be clean up in next release
when the real reading menu is out. :)
now shiftmode and altmode is recoreded in Keys module. So all the UIs
are sharing these two mode instead of remembering their own. These fix
the bug in UI switchings.
For instance, you use combo 'Alt'+'b' to fire up some menu in pdfreader,
the altmode is set, but the alt key was released after the menu show
up. Then the key release event will only be captured by the menu. So
after you exit from the menu, the altmode is still set in pdfreader,
which is not what we want.
