[Hat] hat-trail: attempt to read beyond end of file

[Olaf Chitil]

I guess the source of the problem is the 64bit system. Last time I 
looked at the Hat code a couple of months ago I noticed that for storing 
node references it sometimes uses C ints, sometimes an explicit 4 byte 
type. It assumes these are equivalent...
It should systematically use a 4 byte type. I was too lazy to 
systematically clean all source code.

Ciao,
Olaf