Fix for silly "big mountains" bug.

It's not a real fix, but rather a workaround.
The putchar4x4 routine now checks for writing off-screen.

grafproc.asm

@@ -1903,10 +1903,13 @@ EndPutChar
 ; all pixels are being drawn
 ; (empty and not empty)
 ;--------------------------------------------------
-    ; cpw ydraw #(screenheight-4)
-    ; jcs TypeChar.EndPutChar ;nearest RTS
-    ; cpw xdraw #(screenwidth-4)
-    ; jcs TypeChar.EndPutChar ;nearest RTS
+;	rts
+    cpw dy #(screenheight-1)
+    jcs TypeChar.EndPutChar ;nearest RTS
+	cpw dy #(4)
+    jcc TypeChar.EndPutChar ;nearest RTS	
+    cpw dx #(screenwidth-4)
+    jcs TypeChar.EndPutChar ;nearest RTS
 	; checks ommited.
 	lda plot4x4color
 	beq FontColor0

textproc.asm

@@ -1532,6 +1532,7 @@ DOTNcharloop
     sta dx+1
     lda TextPositionY
     sta dy
+	mva #0 dy+1	; dy is 2 bytes value
     jsr PutChar4x4
 
     inc TextCounter
@@ -1617,6 +1618,7 @@ TypeLine4x4Loop
     sta CharCode4x4
     mwa LineXdraw dx
     mva LineYdraw dy
+	mva #0 dy+1  ;	dy is 2 bytes value
     jsr PutChar4x4 ;type empty pixels as well!
     adw LineXdraw #4
     inc LineCharNr