Consider moving tutorials into namespace agentMET4FOF

[BjoernLudwig]

Now that we have a more ordered structure of packages and modules, we should consider moving the tutorials into the package agentMET4FOF. That means we would be able (and actually have) to import them via

from agentMET4FOF.tutorials.tutorial_1_generator_agent import demonstrate_generator_agent_use

instead of

from agentMET4FOF_tutorials.tutorial_1_generator_agent import demonstrate_generator_agent_use