add get_version function

Change-Id: I7f294d3a0ce1acb961c49a8a9bee0f3e8e2824eb
diff --git a/src/collocatordb.h b/src/collocatordb.h
index 7b9b3f5..af97419 100644
--- a/src/collocatordb.h
+++ b/src/collocatordb.h
@@ -118,4 +118,4 @@
 extern char *get_collocation_scores_as_json(COLLOCATORDB *db, uint32_t w1, uint32_t w2);
 extern char *get_word(COLLOCATORDB *db, uint32_t w1);
 extern void read_vocab(COLLOCATORDB *db, char *fname);
-
+extern char *get_version();