problem building python 3.5 extensions for windows

[Robin Becker]

I have installed VS2015; this is the full version and was a great deal of 
trouble to install. First time out it started whining and I had to 'repair' it.

Anyhow after the 'repair' it said all was OK and no complaints.

However, when I try to use it I don't see options for starting C++ projects, but 
instead only C#.

I get an error like this trying to build for x86 or amd64

          | building 'reportlab.lib._rl_accel' extension
Stderr:  | error: Unable to find vcvarsall.bat

There is a folder "C:\Program Files (x86)\Microsoft Visual Studio 14.0\VC", but 
it doesn't contain any batch scripts. Document 
https://msdn.microsoft.com/en-us/library/x4d2c09s.aspx claims to be about 
VS2015, but has as example

cd "\Program Files (x86)\Microsoft Visual Studio 12.0\VC"

which is presumably not for VS2015.

Any ideas how to get this to work? Should I try a full reinstall of VS2015? I 
can start the VS2015 Developer command prompt, but it doesn't then know about 
the "cl" command.
-- 
Robin Becker