Add blank lines between procedures

[zoziha]

Hello,

It is mentioned in an issue of Fortran stdlib (Add blank lines between procedures) that there is a lack of blank lines between procedures in the f90 files generated by stdlib using fypp, hoping to improve the appearance.

I tried to use fprettify to format the f90 files. It seems that I cannot add blank lines between procedures by fprettify. Can you add this ability to fprettify? It seems to be very practical.

Grateful!