Only load from stdin when `-` option is present
Reading from stdin blocks the user shell so it's a bad cli design to use it by default.
For instance the command
./limaju.py does nothing and user have no idea what to do, moreover he/she may think that the script does not work.
- is commonly used in the unix world for read from stdin instead of a file.
So usage would be:
cat examples/judgments_01.csv | ./limaju.py --input - ./limaju.py --input examples/judgments_01.csv