py2geom: Fix module initialization.
For a typical installation looking like:
$LIBDIR
├── lib2geom.so -> lib2geom.so.1.0.0
├── lib2geom.so.1.0.0
├── pkgconfig
│ └── 2geom.pc
└── python3.7
└── site-packages
└── py2geom
├── __init__.py
└── _py2geom.so
The py2geom init.py must use an absolute import using the fully qualified module name to find the _py2geom library, else the following error would be raised:
from _py2geom import *
ModuleNotFoundError: No module named '_py2geom'