#2 support Prolog-style variable conventions in ccg2xml

[Michael White]

Supporting Prolog-style variable conventions in ccg2xml could enhance the clarity of grammars. In Prolog, variables are capitalized, while atoms are lower case. Using capitalized values -- eg n[Num]/n[Num] -- to indicate that feature variables for the feature 'num' are being used to propagate number information to the result noun category would enhance clarity for those familiar with the traditional use of Prology-style notation in unification. At present, it seems that ccg2xml is doing some uppercasing of feature *names*, which does not seem helpful, perhaps as a misunderstanding of this suggestion back when ccg2xml was first implemented.