KYRA: sound files/classes reorganization step #1

Rename files which are only used for one target.
This is actually wrong for my renaming of sound_towns.
But I'll move the code for other targets to different files in another commit. I want to do just the renaming here, so that Git might be better at preserving the history.

engines/kyra/module.mk

@@ -61,11 +61,11 @@ MODULE_OBJS := \
 	sequence/sequences_hof.o \
 	sequence/sequences_mr.o \
 	sound/sound_adlib.o \
-	sound/sound_amiga.o \
-	sound/sound_digital.o \
+	sound/sound_amiga_lok.o \
+	sound/sound_digital_mr.o \
 	sound/sound_midi.o \
 	sound/sound_pcspk.o \
-	sound/sound_towns.o \
+	sound/sound_towns_lok.o \
 	sound/sound.o \
 	sound/sound_lok.o \
 	text/text.o \