fix colmap convention for the pair id calculation (#150)

Author: lpanaf

glomap/scene/types.h

@@ -1,6 +1,7 @@
 #pragma once
 
 #include <colmap/geometry/rigid3.h>
+#include <colmap/scene/database.h>
 #include <colmap/util/types.h>
 
 #include <cstdint>
@@ -33,7 +34,7 @@ typedef uint64_t track_t;
 
 using colmap::Rigid3d;
 
-const image_t kMaxNumImages = std::numeric_limits<image_t>::max();
+const image_t kMaxNumImages = colmap::Database::kMaxNumImages;
 const image_pair_t kInvalidImagePairId = -1;
 
 }  // namespace glomap