WebUpdate & install directory

[timbojones]

Repro steps:

1. Create a webupdate installer. Deploy to a website.
2. Run the installer. Change the default installation directory; install to e.g. C:\test
3. Change the installer's version number and re-deploy.
4. Run wupdate.exe -or- manually download the new version of the installer .exe and run it

Actual results:

The update wants to install to the original default installation directory, downloading all new files and orphaning the version in the actual installation directory.

Expected results:

The update points to the actual installation directory.

[timbojones]

Note this issue applies to all projects, not just to WebUpdate projects.

This was easy to fix, once I thought of it, by doing

Set Variable %_SB_INSTALLDIR% to ScriptItem->Detect Previous Version

I still contend that this should be default behavior, though that is complicated by the required Product GUID argument. Maybe if the argument is blank, the installer should default to the current Product ID.