Restructure project

src/km3io/_definitions/w2list_genhen.py

src/km3io/_definitions/w2list_gseagen.py

src/km3io/acoustics.py

src/km3io/definitions.py

src/km3io/gseagen.py

src/km3io/offline.py

src/km3io/online.py

src/km3io/rootio.py

src/km3io/tools.py

src/km3io/utils/kprinttree.py