GitLab

* Use relative import to fix pip error

* Update densecrf.pyx

Note on Colab/Kaggle Kernel

Bump version to 1.0

Fix for cython 3.0.0 breaking changes by downgrading to 0.29.36

Fix Cython build dependency with pyproject.toml

Fix Windows MSVC install by updating Eigen Library

Maybe also Fixes #60? The function isn't called anywhere and modern msvc
do define it already, so the definition leads to an error.

Fixes #49 #52

The file `test.py` is now moved into the test folder and pytest directives have been added.

Now it explicitly checks for there to be an all-0 pixel meaning
"unknown" and prints an info about it if it finds one.
This is a try at fixing #30 and #31.