bug report: memory corruption

[AndreyMlashkin]

in the constructor of KDTreeSingleIndexAdaptor, you expect inputData lifetime should be longer rather then Adaptor itself, but it is not always true and user of the code can easily break it.

    KDTreeSingleIndexAdaptor(
        const Dimension dimensionality, const DatasetAdaptor& inputData,
        const KDTreeSingleIndexAdaptorParams& params = {}, Args&&... args)
        : dataset(inputData),
          index_params(params),
          distance(inputData, std::forward<Args>(args)...)
    {

for exmple, calling this would cause indefined behaviour:
ModelKDTreeIndex index(2, std::vector {}, nanoflann::KDTreeSingleIndexAdaptorParams(10));

[AndreyMlashkin]

even worse thing just happened in my code: inputData was implicitly converted and a temporary object was passed to the constructor.
Could you please mark constructor explicit?

[AndreyMlashkin]

@jlblancoc ping

[jlblancoc]

Merged #180. I'll however leave this one open to remember to add a comment to that ctor warning the users about expected lifetimes.
Thanks.

[AndreyMlashkin]

Thanks!
Could you also ping me somehow, I will also create a new version of nanoflan in conan package manager.

[jlblancoc]

@AndreyMlashkin
New release is out! => https://github.com/jlblancoc/nanoflann/releases/tag/v1.4.3

Thanks!