[vtkusers] Allowable C++11 Features in VTK

[Robert Maynard]

As everyone is aware over the past couple of months we have updated
VTK to require a C++11 compiler, but have not explicitly stated what
C++11 features are usable.

We do not intend to incorporate all features of the language at this
time because of incompatibilities with the structure of VTK and/or
incomplete support for the features by all of the compilers that VTK
aims to support.

The current proposed C++11 features, and where they are allowed can be found at:

https://docs.google.com/document/d/1h7wIq25d-qimQO8N9sE43fHXKKlHM2sW2ErohfHiuCg/edit?usp=sharing

Over the next two weeks please provide feedback, either by commenting
on the google document, or replying on the mailing list. Once the two
weeks are over, we will integrate the result into the existing coding
documentation, and then allow C++11 to be used.