Added a color property and a property which is an enumeration {NONTRANSCRIPTIONAL, TRANSCRIPTIONAL} to handle the need to set the outline color for a <zone> and the possible need to output @corresp and @facs attributes in addition to <linkGrp>s.

I've also been working on plans for handling the "modified" property for this collection of classes. Ideally, I want to be able to interrogate the ImtLinkGrpSet object to get the modified state of everything below it, but I also want to be able to set modified at any level rather than going through the hierarchy, so I'm thinking of a setModified() method for all the objects which checks to see if it has a parent; if it does, and the new setting is true, it calls the parent's method instead (thus causing true to propagate up to the top level), but if it's false, it just sets its own modified property, and all those of its children. This means I should be able to read and write at any level and get the required behaviour -- assuming that I always try to read at the highest level. Setters at every level can affect the tree upwards and downwards, depending on whether the value is true or false. It's confusing when you try to explain it, but it will work (I've done something similar, but not as well planned, in Delphi code).