Allow more than one path segment in SILE_PATH
Allow more than one path segment in SILE_PATH

This facilitates using a libraries of SILE related code outside of the
tree SILE happens to be executed from.

neofob/sile,alerque/sile,simoncozens/sile,neofob/sile,neofob/sile,simoncozens/sile,simoncozens/sile,alerque/sile,alerque/sile,neofob/sile,alerque/sile,simoncozens/sile