Bugfixes and alterations to warnings

-Extra error condition in computemap
-Fixed bug in write2cross, columns and rows were confused
-Replaced IRIP with aic in write2cross
-An off-by-1 error fixed in write2cross - The crosses column was removed
for AIC designs but a bug was introduced
-Several fixes to ensure that chromosomes have names in maps
-Removed "subgroups" handling code in mporder. This was related to very
obselete plotgtk code
-Fixed bug in mpprob, design was being treated as a factor
-Changed indentation and added error condition in subset.mpcross