Benchmark requires installation on Windows

[c-lipka]

According to the documentation, as of v3.7 the benchmark should run without having to actually install POV-Ray, and with just the executable binary present.

This is actually not the case for POV-Ray for Windows. Instead, unless a similar version of POV-Ray has already been installed earlier, running POV-Ray for Windows with the /BENCHMARK switch will prompt an error message:

ERROR : Cannot find Home entry in registry (and cannot infer it)

This entry should have been set by the installation program.

POV-Ray can usually infer the installation path but that requires a standard layout of directories, which also seems to be absent.

If you did not install using the correct installation procedure, please do this before running POV-Ray for Windows. You can also try running with the '/INSTALL' or '/INSTALL <bindir> [<docdir>]' option.

[c-lipka]

For the records: This is long-standing behavior, and I suspect it might be non-trivial to fix, so I'm quite confident that we don't want to mess with this as we're preparing for v3.8.0 release. However, we should amend the documention accordingly.