renamed interface.c to client.c

I don't believe "interface" is a good name for something like
"connection by a client to MPD", let's call it "client".  This is the
first patch in the series which changes the name, beginning with the
file name.

src/Makefile.am

@@ -53,7 +53,7 @@ mpd_headers = \
 	inputStream_file.h \
 	inputStream_http.h \
 	inputStream_http_auth.h \
-	interface.h \
+	client.h \
 	list.h \
 	dlist.h \
 	listen.h \
@@ -116,7 +116,7 @@ mpd_SOURCES = \
 	inputStream.c \
 	inputStream_file.c \
 	inputStream_http.c \
-	interface.c \
+	client.c \
 	ioops.c \
 	list.c \
 	listen.c \

src/client.c

@@ -16,7 +16,7 @@
  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  */
 
-#include "interface.h"
+#include "client.h"
 #include "command.h"
 #include "conf.h"
 #include "log.h"

src/directory.c

@@ -20,7 +20,7 @@
 
 #include "command.h"
 #include "conf.h"
-#include "interface.h"
+#include "client.h"
 #include "listen.h"
 #include "log.h"
 #include "ls.h"

src/listen.c

@@ -17,7 +17,7 @@
  */
 
 #include "listen.h"
-#include "interface.h"
+#include "client.h"
 #include "conf.h"
 #include "log.h"
 #include "utils.h"

src/main.c

@@ -16,7 +16,7 @@
  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  */
 
-#include "interface.h"
+#include "client.h"
 #include "command.h"
 #include "playlist.h"
 #include "directory.h"

src/myfprintf.c

@@ -17,7 +17,7 @@
  */
 
 #include "myfprintf.h"
-#include "interface.h"
+#include "client.h"
 #include "path.h"
 #include "utils.h"
 #include "os_compat.h"