Move x.{c,h} to a different subdirectory

x.c has grown into an unmaintainable blob. Moving it in its own
subdirectory is the first step to splitting it into submodules each of
which will have a well defined job so that a lot of the code can be
abstracted to improve readability and make it much easier to maintain.

This process will be done one small part at a time only when we need to
change significantly change a part of the file, there is no need to
break what already works.

Makefile

@@ -6,8 +6,8 @@ include config.mk
 CFLAGS += -I.
 LDFLAGS += -L.
 
-SRC = $(shell ls src/*.c)
-OBJ = ${SRC:.c=.o}
+SRC := $(shell find src/ -name '*.c')
+OBJ := ${SRC:.c=.o}
 
 all: doc dunst service
 
@@ -76,8 +76,8 @@ uninstall:
 test: test/test
 	cd test && ./test
 
-TEST_SRC = $(shell ls test/*.c)
-TEST_OBJ = $(TEST_SRC:.c=.o)
+TEST_SRC := $(shell find test/ -name '*.c')
+TEST_OBJ := $(TEST_SRC:.c=.o)
 
 test/test: ${OBJ} ${TEST_OBJ}
 	${CC} ${CFLAGS} -o $@ ${TEST_OBJ} ${OBJ} ${LDFLAGS}

src/dunst.c

@@ -19,7 +19,7 @@
 #include "notification.h"
 #include "option_parser.h"
 #include "settings.h"
-#include "x.h"
+#include "x11/x.h"
 
 #define LENGTH(X)               (sizeof X / sizeof X[0])
 

src/notification.c

@@ -21,7 +21,7 @@
 #include "rules.h"
 #include "settings.h"
 #include "utils.h"
-#include "x.h"
+#include "x11/x.h"
 
 int next_notification_id = 1;
 

src/settings.h

@@ -4,7 +4,7 @@
 
 #include <stdbool.h>
 
-#include "x.h"
+#include "x11/x.h"
 
 enum alignment { left, center, right };
 enum icon_position_t { icons_left, icons_right, icons_off };

src/x11/x.c

@@ -25,11 +25,11 @@
 #include <string.h>
 #include <unistd.h>
 
-#include "dunst.h"
-#include "markup.h"
-#include "notification.h"
-#include "settings.h"
-#include "utils.h"
+#include "src/dunst.h"
+#include "src/markup.h"
+#include "src/notification.h"
+#include "src/settings.h"
+#include "src/utils.h"
 
 #define WIDTH 400
 #define HEIGHT 400