Add docker support.

[pablospe]

[pablospe]

Maybe for older version of ubuntu the line in between is needed:

RUN apt-get update && \
    DEBIAN_FRONTEND=noninteractive TZ="Europe/Zurich" apt-get install -y --no-install-recommends tzdata && \
    apt-get install -y libeigen3-dev cmake build-essential

I am not going to add this line, just for reference.

[pablospe]

And also relaxing the version of Eigen (for ubuntu 20.04): find_package(Eigen3 3.3.4 REQUIRED)

Again, not going to apply this modification, just for reference when trying older version of ubuntu. The added Dockerfile is using ubuntu 22.04, and works without modifications.

[pablospe]

@vlarsson, if you do sudo apt install libeigen3-dev in ubuntu 20.04, the Eigen version is 3.3.4. Is there any specific reason why to use the 3.4 version? If the alignments aren't a problem in the 3.3.4 version, I would recommend using this version because it will simplify the installation for many people. At least the benchmark seems to work well.