Replace the launcher Icon with a squarer galaxy that doesn't need cropping.

This is a crop of the image of the NGC 4030 galaxy from:
http://www.eso.org/public/images/eso1042e/
This is under a CC license.
Add an About dialog.

This is particularly necessary for the ESO image credit for the
launcher icon.
German translation: Add all strings.

Not all string are really translated but this lets the APK build succeed.
IconsCache: Remove an unnecessary catch.
Update the web launcher icon and add a feature graphic.

These are mostly just placeholders. At least they have the correct
dimensions.