VS2013: improved C++11 conformance

[David Ostrovsky]

Recently compiler baseline was raised to VS 2012 to use improved C++11 
conformance. It turns out that VS2013 has much more C++11 features  [1]:

* Default template arguments for function templates
* Delegating constructors
* Explicit conversion operators
* Initializer lists and uniform initialization
* Raw string literals
* Variadic templates

I wonder if we could raise VS baseline again and require VS2013. 
Particularly this change compiles without problems on VS2013 [2].

[1] 
http://blogs.msdn.com/b/vcblog/archive/2013/06/28/c-11-14-stl-features-fixes-and-breaking-changes-in-vs-2013.aspx
[2] https://gerrit.libreoffice.org/11872

David