Add `md_nws` MIĀ² score based on nominal window size (=10)

Change-Id: I5e431a8ba0f863191f378d447621f3a10039d122
diff --git a/src/collocatordb.h b/src/collocatordb.h
index d601902..7803cd1 100644
--- a/src/collocatordb.h
+++ b/src/collocatordb.h
@@ -106,6 +106,7 @@
   double llr;
   double lfmd;
   double md;
+  double md_nws;
   uint64_t left_raw;
   uint64_t right_raw;
   double left_pmi;