I forked this repo for C++17

[hoytech]

First of all I want to say thanks, lmdbxx has been very useful to me!

For anyone using C++17 in their projects, std::string_view is a very nice complement to LMDB so I integrated it into lmdbxx. Since Arto hasn't checked in for a while, I just want to let anyone browsing here that I will maintain my fork by answering questions and incorporating bugfixes and so on.

Here's the link to my fork: https://github.com/hoytech/lmdbxx