add shifting of argument list in interpreter mode

startup.4th

@@ -2384,6 +2384,9 @@ SYSTEM DEFINITIONS
 \ immediately following the NULL-terminated array of argument pointers
 ARGV ARGC 1+ CELLS+ CONSTANT ENVIRON
 
+VARIABLE ARGV-SHIFT
+0 ARGV-SHIFT !
+
 FORTH DEFINITIONS
 
 \ Convert a C string to a FORTH string by counting the characters
@@ -2400,10 +2403,16 @@ FORTH DEFINITIONS
       2DROP CELL+
    REPEAT ▪ NIP ▪ 2RDROP ;
 
+\ Return ARGC decremented by ARGV-SHIFT, but not less than zero
+: ARGC  ( -- u )  ARGC DUP ARGV-SHIFT @ UMIN - ;
+
 \ Return the string value of the numbered command-line argument
 \ Argument 0 is (normally) the pathname of the current program
 : ARGV  ( u -- c-addr u )
-   DUP ARGC U>= IF DROP 0 0 ELSE ARGV SWAP CELLS+ @ CSTRING THEN ;
+   DUP ARGC U>= IF DROP 0 0 ELSE ARGV SWAP ARGV-SHIFT @ + CELLS+ @ CSTRING THEN ;
+
+: SHIFT-ARGV ( -- c-addr u )
+   0 ARGV 1 ARGV-SHIFT +! ;
 
 UTILITY DEFINITIONS
 
@@ -3018,7 +3027,8 @@ SYSTEM DEFINITIONS
 {
    ONLY FORTH DEFINITIONS
    ARGC 2 U>= IF
-      1 ARGV [[ ' INCLUDED ]] CATCH
+      "SHIFT-ARGV SCONSTANT INTERPRETER" EVALUATE
+      0 ARGV [[ ' INCLUDED ]] CATCH
       DUP EXCP-QUIT = IF
          DROP 2DROP QUIT
       ELSE ?DUP IF