add get_version function

Change-Id: I7f294d3a0ce1acb961c49a8a9bee0f3e8e2824eb
diff --git a/src/collocatordb.cc b/src/collocatordb.cc
index 28035f6..691f820 100644
--- a/src/collocatordb.cc
+++ b/src/collocatordb.cc
@@ -18,6 +18,7 @@
 #include <rocksdb/slice_transform.h>
 #include "merge_operators.h"
 #include "export.h"
+#include "config.h"
 
 #define WINDOW_SIZE 5
 #define FREQUENCY_THRESHOLD 5
@@ -895,6 +896,10 @@
     return strdup(db->collocators2json(w1, db->get_collocation_scores(w1, w2)).c_str());
   }
 
+  DLL_EXPORT const char *get_version() {
+    return PROJECT_VERSION;
+  }
+
 #ifdef __clang__
 #pragma clang diagnostic push
 #endif