Add simple tokenizer

os.h

@@ -0,0 +1,13 @@
+
+#include "s8slice.h"
+
+enum {
+	OS_READ  = 1<<0,
+	OS_WRITE = 1<<1,
+	OS_ALLFLAGS = (1<<2)-1
+};
+typedef unsigned int os_open_flags;
+
+S8Slice os_open_file(S8Slice path, os_open_flags flags);
+
+S8Slice os_close_file(S8Slice file);