add optimizations when compiling trimspNL

- this shortens the runtime a simulation significantly (by a factor of ~2).
- the output from trimspNL is identical to when no optimizations are used

fortran/Makefile

@@ -19,7 +19,7 @@ OPS=-c $(DIALECT) $(WARN) $(DEBUG)
 all : trimspNL
 
 trimspNL : trimspNL.F
-	$(FC) -o $@ $< 
+	$(FC) -O3 -o $@ $< 
 
 clean:
 	rm -f *.o *~ \#* .#* trimspNL