Addresses issue #161

Adds new options HEADERROR and FLOWCHANGE to provide more rigorous criteria for hydraulic convergence. Also breaks HYDRAUL.C into 3 separate files to improve code readability.

src/inpfile.c

@@ -618,6 +618,8 @@ int saveinpfile(EN_Project *pr, char *fname)
   fprintf(f, "\n CHECKFREQ           %-d", hyd->CheckFreq);
   fprintf(f, "\n MAXCHECK            %-d", hyd->MaxCheck);
   fprintf(f, "\n DAMPLIMIT           %-.8f", hyd->DampLimit);
+  fprintf(f, "\n HEADERROR           %-.8f", hyd->HeadErrorLimit * pr->Ucf[HEAD]);
+  fprintf(f, "\n FLOWCHANGE          %-.8f", hyd->FlowChangeLimit * pr->Ucf[FLOW]);
 
   /* Write [REPORT] section */