write out centromere features as a misc_feature

git-svn-id: svn+ssh://svn.internal.sanger.ac.uk/repos/svn/pathsoft/artemis/trunk@13727 ee4ac58c-ac51-4696-9907-e4b3aa274f04

etc/key_mapping

@@ -18,4 +18,5 @@ dinucleotide_repeat_microsatellite_feature misc_feature    note=dinucleotide_rep
 EST_match                                  misc_feature    note=EST_match
 match_part                                 misc_feature    note=match_part
 direct_repeat                              repeat_region   rpt_type=direct
-polypeptide_domain                         misc_feature
\ No newline at end of file
+polypeptide_domain                         misc_feature
+centromere                                 misc_feature    note=centromere
\ No newline at end of file