Slicer3:Extensions:Directories

TemporaryDirectory is user-defined via Application Settings (defaults to /Users/$USER/Slicer3$USER on a Mac)

ExtensionsInstallPath is user-defined via Application Settings, defaults to value of TemporaryDirectory if not set by user

• Zip files downloaded to TemporaryDirectory
• Extensions installed to Slicer3 SVN Revision-based subdirectory of ExtensionsInstallPath (for example, /Users/$USER/Slicer3$USER/@SVN@)
• After download and install of the new extension, ExtensionsInstallPath/@SVN@/$ExtensionName is added to the Application's ModulePaths.
• @SVN@ is the svn revision number of the repository from Slicer3Version.txt for the build.
• Slicer3 "default" extensions in Slicer3_INSTALL_MODULES_LIB_DIR
• On startup, Slicer3 will search all potential module paths, substituting @SVN@ with the value recorded in Slicer3Version.txt

TODO:

Check all subdirectories of the ExtensionsInstallPath and see if a previous version had downloaded an extension and if it's not available in the current version, then query the user to download it.