Ensure DHIRES mode is exited when exiting to BASIC

Recent MAME with Video-7 seems to get into a weird state when exiting
to BASIC e.g. running a program, since AN3 is not fully reset. Do it!

RELEASE-NOTES.md

@@ -33,6 +33,7 @@ Project Page: https://github.com/a2stuff/a2d
 * Ensure the modification date for copied folders matches the original.
 * Prompt to re-insert system disk when launching Apple Menu items.
 * Add Text-to-Speech file type ($D9) and icon.
+* Ensure DHIRES mode is exited when exiting to BASIC.
 
 ### Selector
 

desktop/main.s

@@ -2945,6 +2945,7 @@ ResetHandler    := CmdQuitImpl::ResetHandler
         sta     ALTZPON
         jsr     SetColorMode    ; depends on state in Aux LC
         sta     CLR80VID        ; back off, after `SetColorMode` call
+        sta     DHIRESOFF
         sta     ALTZPOFF
         bit     ROMIN2
 

res/notes/testplan.md

@@ -883,6 +883,8 @@ The following tests all require:
 
 * On an RGB system (IIgs, etc), go to Control Panel, check RGB Color. Verify that the display shows in color. Preview an image, and verify that the image shows in color and the DeskTop remains in color after exiting.
 * On an RGB system (IIgs, etc), go to Control Panel, uncheck RGB Color. Verify that the display shows in monochrome. Preview an image, and verify that the image shows in color and the DeskTop returns to monochrome after exiting.
+* Using MAME (e.g. via Ample), configure a system with Machine Configuration > Monitor Type > Video-7 RGB. Start DeskTop. Open a window. Apple Menu > Run Basic Here. Type `HGR : HCOLOR=3 : HPLOT 0,0 TO 100,100`. Verify a diagonal line appears.
+
 
 ### Z80 Card
 

selector/app.s

@@ -957,6 +957,7 @@ noop:   rts
         ;; Switch back to color DHR mode
         jsr     SetColorMode
         sta     CLR80VID        ; back off, after `SetColorMode` call
+        sta     DHIRESOFF
 
         rts
 .endproc ; RestoreTextMode