Fix error in fluence for dosxyznrc sources 1 and 7

Change minus sign to plus sign for particles which miss the geometry in
the fluence calculation. Previously, particles that missed the geometry
were subtracted from the total fluence (used to normalize the dose).
This bug has been there for years, indicating, hopefully, how rarely
these sources are used.

HEN_HOUSE/user_codes/dosxyznrc/dosxyznrc.mortran

@@ -2908,9 +2908,9 @@ ELSEIF((enflag=1)|(enflag=2)|(enflag=3)|(enflag=4))[ ;OUTPUT61 etot/esrc;
 
 "Calculate incident fluence
 IF(isource = 0 | isource = 1 | isource = 3 | isource = 7)[
-   temp2=dble(IHSTRY+ncaseold-nsmiss-nmissm);
-   IF(beamarea = 0)[ ainflu=dble(IHSTRY+ncaseold-nsmiss-nmissm);]
-   ELSE[             ainflu=dble(IHSTRY+ncaseold-nsmiss-nmissm)/beamarea;]
+   temp2=dble(IHSTRY+ncaseold+nsmiss+nmissm);
+   IF(beamarea = 0)[ ainflu=dble(IHSTRY+ncaseold+nsmiss+nmissm);]
+   ELSE[             ainflu=dble(IHSTRY+ncaseold+nsmiss+nmissm)/beamarea;]
 ]
 ELSEIF(isource = 2 | isource = 8 )[
    ainflu=dble(IHSTRY+ncaseold+nsmiss+