shared objects

[Christian Kamm]

> I gave it a try but I didn't succeed, maybe you could help me again:

Two things:
First, remove the 'export'. For me, it doesn't work with it.
Second, you defined a square.squareIt in your libsquare.so, but try to  
access it as libsquare.squareIt. Either put a 'module libsquare;'  
statement in square.d or use D's interface files: dmd -H should create  
such a file from your square.d. Then the compiler will use it when  
compiling with dmd app.d -L-lsquare.

Cheers,
Christian