bunch of updates

 - added verbose option to usageString
 - compFields toString shows base path
 - FieldStringPrettyPrint optionally omits field with pathnames
 - PrimSig provides null values for fields if the tag is missing in the
data
 - URLPrepper correctly escapes parameters in url
 - bug in AttributeToChildNodeProcessor
 - subfieldcollector applies itself to all inner structures too