HelloWorld! using a library on SailfishOS 2

This is the second edition of a little hello world project for SailfishOS that makes use of a library. It will show how you

• can build your own libraries
• present the properties therein to the QML layer
• deploy it with your SailfishOS application

You find the example on Github.

I am still not 100% happy with this version, but it is the only way I managed to use TEMPLATE=subdirs in .pro files with the SailfishOS SDK. Currently the SDK expects the project directories to be arranged so that the 'rpm' directory is on the main project directory level. And that is exactly not what I want. Well, it's doable, just put the main .pro file in the directory of your SFOS project.