Move header files to subdirectory

Since slweb is meant as a library, it is advisable to keep public header
files under their own directory in order to avoid name clashing i.e.,

 #include "something.h"

Now becomes:

 #include "slweb/something.h"

1 files changed, 4 insertions, 4 deletions

diff --git a/handler.c b/handler.c
index 1d7e922..f29da15 100644
--- a/handler.c
+++ b/handler.c
@@ -1,9 +1,9 @@
 #define _POSIX_C_SOURCE 200809L
 
-#include "handler.h"
-#include "http.h"
-#include "server.h"
-#include "wildcard_cmp.h"
+#include "slweb/handler.h"
+#include "slweb/http.h"
+#include "slweb/server.h"
+#include "slweb/wildcard_cmp.h"
 #include <errno.h>
 #include <stdbool.h>
 #include <stddef.h>