* add past paths for empty arguments etc
* cache attribute token transform pipelines
* fix bugs in TokenCollector and NoIncludeOnly handler, and improve its
efficiency by only registering for 'end' tokens on demand
* Remove empty reset methods from a few handlers
* Add a simple 'ap' debug print function that makes it easy to only print some
debug prints by temporarily changing 'dp' to 'ap'
* Improvements and bug fixes in AttributeExpander
Change-Id: Ie69729c8f62d48bba922712e44ebce484c621c50