TODO.catalogs

* ISSUES:
** do not use NetworkLibrary instance in AllCatalogsActivity, send result via intent
** do not use myChanged state flag in AllCatalogsActivity, use setResult immediately

* SHORT-TERM (1.8.3)
 + check recently added catalogs are not lost (and are visible) after update
 + newly added catalog is not checked in filter activity
 + use language filter to detect visible catalogs on first start
 + add catalog icons
 + order catalogs alphabetically
 + extract litres API to a separate branch
 + add RSS catalog
 + hardcoded strings ("Active/Inactive catalogs", may be some else?) => en.xml
 + "Library filter" => "All catalogs"
 + NetworkLibraryFilterActivity => AllCatalogsActivity
 + make a separate branch for catalogs + master
 + copyrights in all files

* MID-TERM
** litres catalog use litres-api

* LONG-TERM
** re-order catalog function

* PLUGIN
** self-service kiosk: update instruction
** gift coupon activation
** mobile operators topup