Wingspan correction does not allow limit values

## Type of issue
- [x] bug report

## Description
In `read_config.py`, function `check_config` and in `calc_cont.py` function `apply_wingspan_correction`, the valid aircraft wingspan is set to be 20.0 < b < 80.0, but it should be 20.0 <= b <= 80.0 (allowing limit values).
