* Improve bzr completion. Closes#3661
* Add basic completion for bzr commands
* Include short and log options for common commands
* Removed not so common commands
* Remove trailing '.' as requested by #3769
* Remove '=' as suggested by #3769
* We don't need '=' in long options
* Use fish helper functions for autocomplete
To avoid issues pointed out in #3769 helper functions included in fish
are used (__fish_use_subcommand and __fish_seen_subcommand).
* Fixed typo
