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* New backend GPSIES for www.gpsies.com
* New: Command line utility "gpxdo" exposing commands for listing, copying,
merging, removing, editing, fixing, comparing
* New class BackendDiff
* Backend: rename copy_all_from to sync_from and add parameters
* hide class Authenticate from public API
* Define assumption about points having to be ordered by time
* Do not use slow GPX.get_time_bounds()
* Track.last_time now is a property
* MMT: Map Track.keywords to MMT tags
* Track.keywords now returns them sorted
* MMT: login only once per backend instance
* Make list(Track) sortable (by title)
* New: Track.adjust_time()
* Track: Improve __str__ and __repr__
* Backend can now be used as an iterable
* New class BackendDiff
* MMT now supports life tracking
* New generator Track.segments()
* Simplify usage of auth.conf
* fix illegal XML generated by gpxy for GPX 1.1
* New: Backend.match implements client-side filtering
* New: BackendException
* New: Map values for "what" between different backends
* New: Backend.legal_whats shows the values for "what" supported by a backend