Craftitude Repository System, draft version 0.4b.

+ Package Instructions for all platforms now in subfolder "all" (a.k.a. "all platforms")
  -> Applies to not-platform-dependent packages, too.
+ Added "HasPlatformDependentFiles" to Package Metadata
+ Added "HasPlatformIndependentFiles" to Package Metadata
- Removed "PlatformDependency" completely from Package Metadata.
- Removed "ID" completely from Package Metadata.