[r6rs-discuss] [Formal] Remove the (r6rs when-unless) library

[AndrevanTonder]

I do not personally like one-armed IF, but let me point out that AND/OR 
can also be used instead of WHEN/UNLESS.  In fact, AND/OR can be more concise 
than WHEN/UNLESS when there is more than one condition.  Having said that, 
using AND/OR this way does feel somewhat artificial in some cases, and I would 
in some cases rather use WHEN/UNLESS if it were standardized.  In such a case, 
I would prefer it to be in the base library.

Andre