[CLN-list] CLN switched to C++11

[Bruno Haible]

Hi Richy,

> I've just just bumped the minimum C++ language support for the compiler 
> to C++11.

Unfortunately, this removes the ability to build with the MSVC compiler:
The configuration bails out with
  configure: error: *** A compiler with support for C++11 language features is required.

This is with MSVC 14 (Visual Studio 2015) [1] which is quite recent.

The '#ifdef _MSC_VER' in include/cln/number.h shows that there is some
interest in having MSVC support, no?

Bruno

[1] https://en.wikipedia.org/wiki/Microsoft_Visual_Studio#2015