Describe the bug

-fplc flag doesn't seem to work if -plc isn't specified.

This command works fine:
$ pigo -in image.jpg -out output.jpg -cf ../pigo/cascade/facefinder -plc ../pigo/cascade/puploc -flpc ../pigo/cascade/lps

But running the following only detects the face but not its facial landmarks:
$ pigo -in image.jpg -out output.jpg -cf ../pigo/cascade/facefinder -flpc ../pigo/cascade/lps

Expected behavior

-flpc should work without -plc as per the screenshot https://user-images.githubusercontent.com/883386/66802771-3b0cc880-ef26-11e9-9ee3-7e9e981ef3f7.png