Ressurect move.cpp

Actually it is san.cpp renamed. Because now has the move
conversions functions and doesn't have any more the bulky
move_from_san(), it is better to call it move.cpp

Remove san.h while there.

No functional change.

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

src/position.cpp

@@ -36,7 +36,6 @@
 #include "position.h"
 #include "psqtab.h"
 #include "rkiss.h"
-#include "san.h"
 #include "tt.h"
 #include "ucioption.h"