Ensure that the test files are recompiled in the target directory
Ensure that the test files are recompiled in the target directory

If you don't do that, you get the following error with Python 3.6

```
import file mismatch:
imported module 'test_quadtree' has this __file__ attribute:
  /home/user/code/simple_quadtree/tests/test_quadtree.py
which is not the same as the test file we want to collect:
  /home/user/code/simple_quadtree/target/tests/test_quadtree.py
HINT: remove __pycache__ / .pyc files and/or use a unique basename for your test file modules
```

stefano-m/simple_quadtree