neaten up the sourec file list to make future changes easier

frontends/riscos/Makefile

@@ -46,17 +46,51 @@ endif
 # ----------------------------------------------------------------------------
 
 # S_RISCOS are sources purely for the RISC OS build
-S_FRONTEND := assert.c bitmap.c buffer.c configure.c gui.c	\
-	dialog.c download.c filetype.c font.c help.c image.c	\
-	iconbar.c menus.c message.c mouse.c palettes.c plotters.c	\
-	print.c query.c save.c save_draw.c save_pdf.c schedule.c	\
-	search.c searchweb.c textarea.c	textselection.c theme.c		\
-	theme_install.c toolbar.c url_suggest.c wimp.c wimp_event.c	\
-	ucstables.c uri.c url_complete.c url_protocol.c	window.c	\
-	corewindow.c cookies.c hotlist.c			\
-	local_history.c global_history.c				\
-	$(addprefix content-handlers/,artworks.c awrender.s draw.c	\
-	sprite.c)							\
+S_FRONTEND :=			\
+	assert.c		\
+	bitmap.c 		\
+	buffer.c		\
+	configure.c		\
+	cookies.c		\
+	corewindow.c		\
+	dialog.c		\
+	download.c		\
+	filetype.c		\
+	font.c			\
+	global_history.c	\
+	gui.c			\
+	help.c			\
+	hotlist.c		\
+	image.c			\
+	iconbar.c		\
+	local_history.c		\
+	menus.c			\
+	message.c		\
+	mouse.c			\
+	palettes.c		\
+	plotters.c		\
+	print.c			\
+	query.c			\
+	save.c			\
+	save_draw.c		\
+	save_pdf.c		\
+	schedule.c		\
+	search.c		\
+	searchweb.c		\
+	textarea.c		\
+	textselection.c		\
+	theme.c			\
+	theme_install.c		\
+	toolbar.c		\
+	url_suggest.c		\
+	ucstables.c		\
+	uri.c			\
+	url_complete.c		\
+	url_protocol.c		\
+	window.c		\
+	wimp.c			\
+	wimp_event.c		\
+	$(addprefix content-handlers/,artworks.c awrender.s draw.c sprite.c) \
 	$(addprefix gui/,button_bar.c progress_bar.c status_bar.c	\
 	throbber.c url_bar.c)						\
 	$(addprefix configure/,con_cache.c con_connect.c con_content.c	\