Introduce notation.h

And group there all the formatting functions but
uci_pv() that requires access to search.cpp variables.

No functional change.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>

src/position.cpp

@@ -25,6 +25,7 @@
 
 #include "bitcount.h"
 #include "movegen.h"
+#include "notation.h"
 #include "position.h"
 #include "psqtab.h"
 #include "rkiss.h"