Updated icons, fixed DPI-related issues

Updated app with new SVMP icons.
Added larger sizes for "ic_launcher" icons (upscaled).
Added code to get icons for specific sizes.
Added checks for tablet icon sizes (one size larger than normal).
Updated API checks to use version numbers instead of names.
Fixed issue where default icons wouldn't be sized correctly on
some screens.
Fixed issue where app icon overlays wouldn't be sized correctly on
some screens.