Fixed 'I 1 2 1' issue: it was actually a bug rather than a "feature", we were parsing everything in symoplib but some space groups happened to have alternative names and 'I 1 2 1' is the alternative name of 'I 2" which we were allowing. Now parsing and storing in lookup map both names.
Fixed also a bug by which the last space group in file was not added to the lookup-by-name map