Merge remote-tracking branch 'suutari-ai/sales-units' into sales-units

* suutari-ai/sales-units:
  wip
  wip:short_name -> symbol (update usages)
  wip: format number util
  wip: admin: display unit editing template
  wip:new unit tests for the units
  wip: line unit mixin
  doc: Document the new units system
  doc: Add Django model autodoc extension
  ShopProduct: Fix bug in purchase multiple checking
  smaller_p/larger_p
  wip: smaller_p/larger_p msg all languages
  rename short_name to symbol
  wip:remove-xxx-todo-marks
  wip: smaller_p/larger_p msg all languages
  wip: swedish trans of the changed msg
  wip
  rename short_name to symbol
  wip:fix typo
  wip:remove commented code
  wip:fix basket update
  wip: improve django_sphinx a bit
  wip: docs and api improvement
  wip:docs
  wip:unit compatibility
  wip:display precision
  wip:trans update(no real changes)
  wip:trans update(no real changes)
  wip:more tests
  wip: improve backward compatibility
  wip:improve backward compatibility
  wip
  wip:tune message
  wip:messages.fi
  wip:base messages (allow bare number)
  wip: remove comment
  wip: front: price -> unit price
  wip:is_countable -> allow_bare_number
  wip MOVE TO FRONT: (unrelated message file update, fi_FI)
  wip:messages
  wip:messages
  wip:messages
  wip:messages
  wip: update one text and its english trans file
  wip: update en translations
  wip
  wip:all
  wip
  wip: remove hidden input hack from product page
  wip
  wip.evertyhing
  wip:doc
  wip
  wip: sales unit display stuff