Breaks on version 6 of gcc/g++

[petroseskinder]

Documentation may need to be updated.

According to the documentation, our system needs g++ version 4.9+ for parconnect to successfully compile.

Because of the plus mark, I thought this meant I could use g++ version 5 and 6. However, when I attempted it on g++-6.0, I was met with the following errors.

Since I was able to successfully compile it with g++-4.9, I believe 6.0 serves as an upper bound in terms of support. That said, because I didn't test it with g++ 5.0, this may not be the tightest upper bound.

[cjain7]

I resolved errors at my end and its compiling with g++ 6.1 now. Thanks!