kernel: separate headers into kernel and user headers

all kernel headers have been moved from include/mango to include/kernel
and include definitions that are only relevant to kernel-space.

any definitions that are relevant to both kernel- and user-space
(i.e. type definitions, syscall IDs) have been moved to
include/mango within libmango.

libmango/include/mango/status.h

@@ -0,0 +1,23 @@
+#ifndef MANGO_STATUS_H_
+#define MANGO_STATUS_H_
+
+typedef unsigned int kern_status_t;
+
+#define KERN_OK               (0)
+#define KERN_UNIMPLEMENTED    (1)
+#define KERN_NAME_EXISTS      (2)
+#define KERN_INVALID_ARGUMENT (3)
+#define KERN_UNSUPPORTED      (4)
+#define KERN_NO_MEMORY        (5)
+#define KERN_NO_ENTRY         (6)
+#define KERN_WOULD_BLOCK      (7)
+#define KERN_BUSY             (8)
+#define KERN_NO_DEVICE        (9)
+#define KERN_DEVICE_STUCK     (10)
+#define KERN_IO_ERROR         (11)
+#define KERN_FATAL_ERROR      (12)
+#define KERN_BAD_STATE        (13)
+#define KERN_MEMORY_FAULT     (14)
+#define KERN_ACCESS_DENIED    (15)
+
+#endif