This PR resolves the issue #214
It causes issues when using opencv and pcl together if we use the kdTree from pcl which uses flann. This is a very frequent case where keeping in mind the include order as this does not seem right. And USE_UNORDEREDMAP macro is a very generic name, if guarded with a FLANN prefix it makes sure that no collision happens with other libraries.
This PR resolves the issue #214 It causes issues when using opencv and pcl together if we use the kdTree from pcl which uses flann. This is a very frequent case where keeping in mind the include order as this does not seem right. And USE_UNORDEREDMAP macro is a very generic name, if guarded with a FLANN prefix it makes sure that no collision happens with other libraries.