Add installation and packaging targets

[feegeer]

to run the container / get the created packages, run:

docker build -t cpack-exercise .
docker run --rm -it --mount type=bind,source="$(pwd)",target=/mnt/cpack-exercise cpack-exercise

I worked on the following bonus tasks:

Fix more errors and warnings (not necessarily all)

before:

after:

• I added an extended description
• I fixed the malformed-contact error by using the correct syntax
• I added a directory ./debian with files for the license and the changelog as well as a manpage, each with the according syntax

Let us completely automatize the package creation using the Docker image

see comand above to run the container and obtain the .tag.gz and .deb files