Add Atari version of of doesclrscrafterexit().

- Update documentation.
- Update atari.h and apple2.h header files.
- Adapt Atari test/target programs.
- Fix a typo in "div" entry in funcref.sgml.

libsrc/atari/doesclrscr.s

@@ -0,0 +1,19 @@
+;
+; Christian Groessler, June-2016
+;
+; unsigned char doesclrscr(void);
+;
+; returns 0/1 if after program termination the screen isn't/is cleared
+;
+
+        .export  _doesclrscrafterexit
+        .import  __dos_type
+        .include "atari.inc"
+
+_doesclrscrafterexit:
+        ldx     #0
+        lda     __dos_type
+        cmp     #MAX_DOS_WITH_CMDLINE + 1
+        txa
+        rol     a
+        rts

libsrc/atari/is_cmdline_dos.s

@@ -7,14 +7,9 @@
 ;
 
         .export  __is_cmdline_dos
-        .import  __dos_type
-        .include "atari.inc"
+        .import  _doesclrscrafterexit
 
 __is_cmdline_dos:
-        ldx     #0
-        lda     __dos_type
-        cmp     #MAX_DOS_WITH_CMDLINE + 1
-        txa
-        rol     a
-        eor     #$01
+        jsr     _doesclrscrafterexit    ; currently (unless a DOS behaving differently is popping up)
+        eor     #$01                    ; we can get by with the inverse of _doesclrscrafterexit
         rts

libsrc/atari/targetutil/w2cas.c

@@ -35,7 +35,7 @@ static struct __iocb *findfreeiocb(void)
 static void exitfn(void)
 {
     /* if DOS will automatically clear the screen, after the program exits, wait for a keypress... */
-    if (! _is_cmdline_dos())
+    if (doesclrscrafterexit())
         cgetc();
 }