Missing entries in Logger.add #105

Is it possible for Logger:add(s) to add only a subset of the variables? For instance, I would like to call Logger:setNames({'loss', 'epoch', 'batch'}) and then do Logger:add({loss=0.5, batch=10}). The unknown field epoch should be set to a default value, say zero.

I think the current version of Logger is designed to only take as argument an ordered array (?). In the above example, if I do Logger:add({0.5, 10}), it will simply set the epoch to 10 and leave batch blank. This behavior is quite a pain while logging lots of variables.