* Renamed DownloadFile to DownloadLocatedFile.
* Pulled a generalized rule DownloadFile out of DownloadOptionalPackage.
* Added InstallSourceArchive rule which can be used in OptionalPackages to
add sources for installed packages to the image.
* Added configure option --include-sources to enable including the sources
for third party software in the image.
git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@35617 a95241bf-73f2-0310-859d-f6bbb57e9c96