[plt-scheme] release of 4.0

[Prabhakar Ragde]

Matthias wrote:

> Due to (un)foreseen problems that crept into the release process, we  
> are postponing the release of version 4.0 until early/mid June.

Thanks for the update. Am I right in assuming that this pushes 4.1 to 
past the start of the school year (for us, after Labour Day)? --PR