added AV_codec.h to public headers
renamed AV_codec to toxmedia
Merge pull request #635 from Martijnvdc/master

added AV_codec.h to public headers
Offer solution for "error while loading shared libraries: libtoxcore.so.0: cannot open shared object file: No such file or directory".

Offer solution for "error while loading shared libraries: libtoxcore.so.0: cannot open shared object file: No such file or directory".
Merge pull request #636 from fr0stycl34r/patch-1

Offer solution for "error while loading shared libraries: libtoxcore.so....