transport-xmpp: added AUTHORS file
Add "About" button to main and transport-xmpp
main: nonNLSStrings s/tab/4spaces/
transport-xmpp: MemorizingTrustManager bump
transport-xmpp: Use Context again

c2aa574 switched from Context to Application. This is now not longer
needed, we just have to make sure to use either an Application, Service
or Activity instance in the right places.
Fix HTML links in about dialogs

It was not possible to actually click on the hyperlinks, since this is
only possible if the content is just a message. Only Views allow
clickable HTML content, therefore we now use one.
main: importexportsettings.xml buttons 50/50

Made the two buttons use 50% of the available space.
main: importexportsettings formatting only