Seek for resources in both bundled and downloaded resources directory

[ForNeVeR]

Currently, we allow auto-downloading of certain content to the Paths.DownloadsDirPath, but resource lookup only looks in Paths.BundlerResourceDirPath.

1. Figure out what content gets downloaded exactly: only maps or anything else?
2. Make sure we enumerate the file system properly when looking up maps and other kinds of downloadable content: we should look in both bundled resource dir and in the downloads folder.