[m-rev.] for review: io.make_temp now reterns a result rather than throw exceptions

[Sebastian Godelet]

Hi Paul,

> It seems better to improve the C# implementation.  We just haven't done
> that yet.

The work I've done for the make_temp_directory could be easily applied to temporary files,
e.g. instead of using DirectorySecurity use FileSecurity.
Although I'd have to rebase my changes to the latest master.
Have you tested those changes already? It was working fine using Fedora 21 and mono 4.0+,
Windows .NET 4.6.1, Windows using mono 4.0+
I don't have access to a MacOS X system though or an older mono version.

Cheers,

Sebastian