install-path %windows-stuff%

[Gankra]

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.

[ChrisDenton]

On Windows people will often be given two options: install for the current user or for all users. In both cases you'd normally use a KNOWNFOLDERID with the SHGetKnownFolderPath function (see also the dirs crate which exposes a few of these).

• Current User: FOLDERID_LocalAppData is usually used (which is C:\Users\Chris Denton\AppData\Local on my system). Some applications use the Programs sub directory (e.g. C:\Users\Chris Denton\AppData\Local\Programs), which makes sense to me but is far from universal.
• All users: FOLDERID_ProgramFiles (e.g. C:\Program Files). Or maybe FOLDERID_ProgramFilesX64 if you have a 32-bit installer installing a 64 bit application (otherwise a 32-bit application on x64 gets redirected to C:\Program Files (x86)).