We should really remove the placeholder.txt from the releases and the development code. There is simply no need to use such thing.
After this is done, every reference for this file should be removed from the code of the core too, making things more simple.

@Nick: if there is a zip program that ignores empty directories, there should be an option to change that behavior or just use some other program to create the important files (those that are to be released and distributed).