works with (Strawberry) Perl 5.010 from 2009, so require that version; move to older File::Path interface

Generate and install .conf files (with heavy lifting from tdonovan!). Install sample docroot (if the top directory doesn't exist). Change installation of error and icons directories to match Unix -- only if the top directory doesn't exist. Provide a simple Perl script to help with non-standard copy semantics used by the install. THIS ADDS PERL AS A BUILD PREREQ. (The VisualStudio-specific Windows build system required it too.)