problems with xc7.1.89

[Massimo Campostrini]

More problems with the the snapshot xc7.1.89:

xshowimf/imf2x are broken when writing 16x16 bitmaps 
(this was working in 7.1.87).

I found a way to crash xshowimf; I have a crude fix for this, 
but I will try to fix it The Right Way.

-- 
        Massimo Campostrini, 
Istituto Nazionale di Fisica Nucleare, Sezione di Pisa.
WWW home page: http://www.difi.unipi.it/~campo/