Fix broken div10_FAC1

Also add some unit tests for div_FAC1_FAC2

src/basic/math/bafe.div10_FAC1_p.s

@@ -7,7 +7,7 @@
 ; Math package - divide FAC1 by 10, result is always positive
 ;
 ; Notes:
-; - shifts FAC1 to FAC2, loads FAC1 with the constant 10, falls through to the division routine
+; - moves FAC1 to FAC2, loads FAC1 with the constant 10, jumps to the division routine
 
 ;
 ; See also:
@@ -16,14 +16,11 @@
 ; - https://codebase64.org/doku.php?id=base:kernal_floating_point_mathematics
 ;
 
-; XXX test this
-
 div10_FAC1_p:
 
-	lda #$00
-	sta FAC1_sign
+    jsr mov_FAC1_FAC2
+    ldy #>const_TEN
+    lda #<const_TEN
+    jsr mov_MEM_FAC1
 
-	ldy #>const_TEN
-	lda #<const_TEN
-
-	jmp div_MEM_FAC1
+    jmp div_FAC2_FAC1