install-path %windows-stuff%

install-path should support an option to install to "the proper place" on windows. Can't remember all the %options% and which ones are the Good Ones. This wouldn't make sense on unix but with #286 we can just ignore it in the cascade on those platforms.

Start by reviewing issue #286 and the existing install-path cascade, then determine which Windows installation locations and options are considered appropriate. Done means defining a Windows-specific install-path option while preserving the Unix behavior described in the issue.

Written by the indexing model from the issue text.