slightly update sfmake.inc
added environment variable FPATH so that scifor module can be used directly without makefile where needed
[I tried to generate a less intrusive compilation using env FPATH, though it works for STD and OPT options I can not find
a way to use it with DEB option because modules have to be stored in different places. One possibility here is to give up
debugged library or to limit its use to few cases where it is really needed, indeed the library reached a decent stability]