Initialize landscape with parametrizable number of nests of different species

This assumes that nests are eternal which will probably not stay this way, but I would like to keep it simple for now.

It also does not use a system, neither for initialization, nor for event generation, as for now nothing would be gained except overhead.

The manual creation of Protobuf events is a bit verbose IMHO, but I guess that is the price to reliably communicate across language boundaries.