c++ wrapper

[audionuma]

Hello,

while working on a c++ project, I ended trying to implement a lightweight c++11 wrapper for libebur128.

The result can be seen here : https://github.com/audionuma/libebur128/commit/c6cd6e6fc0c9e55a92ee9b2030eb839e498f03cc

Before submitting a pull request, I thought that it would be nice if some c++ expert (which I am not) could check for bad design.

It you feel that it is worth merging into the upstream repo, I'll be glad to submit a pull request.

Cheers,

Manuel