add iob_free and man page for iob_reset.

check in some windoze compat crap (still does not compile through for
windoze)

buffer/buffer_close.c

@@ -1,13 +1,22 @@
 #include <buffer.h>
 #include <stdlib.h>
 #include <unistd.h>
+#ifdef __MINGW32__
+#include <windows.h>
+#else
 #include <sys/mman.h>
+#endif
 
 void buffer_close(buffer* b) {
   if (b->fd != -1) close(b->fd);
   switch (b->todo) {
   case FREE: free(b->x); break;
-  case MUNMAP: munmap(b->x,b->a); break;
+  case MUNMAP:
+#ifdef __MINGW32__
+    UnmapViewOfFile(b->x);
+#else
+    munmap(b->x,b->a); break;
+#endif
   default: ;
   }
 }