Use fg/b/me from screen.4th instead of literals

MFC after:	3 days
X-MFC-to:	stable/10

sys/boot/forth/menu.4th

@@ -216,13 +216,10 @@ also menu-infrastructure definitions
 	dup menuX @ swap at-xy
 
 	\ Print the value of menuidx
-	loader_color? if
-		." " (  )
-	then
+	loader_color? dup ( -- bool bool )
+	if b then
 	menuidx @ .
-	loader_color? if
-		." " (  )
-	then
+	if me then
 
 	\ Move the cursor forward 1 column
 	dup menuX @ 1+ swap at-xy

sys/boot/forth/version.4th

@@ -85,11 +85,10 @@ only forth definitions also version-processing
 	dup versionX @ swap - versionY @ at-xy
 
 	\ Print the version (optionally in cyan)
-	loader_color? if
-		." " type ." "
-	else
-		type
-	then
+	loader_color? dup ( -- bool bool )
+	if 6 fg then
+	type
+	if me then
 ;
 
 only forth definitions