Reader: Magnifying glass's size and zoom level are not saved at exit/restored at start

[vedgy]

I have noticed these possible omissions while implementing #189. Configuration::getConfiguration().setMagnifyingGlassSize() exists but is never called. A fortunate side effect is that invisible/lost (due to a bug fixed in #189) Magnifying glass can be restored by simply restarting YACReader rather than by manually editing the configuration file. There is no save/restore support for Magnifying glass's zoom level at all.