Template breadcrumb - only remove last seperator

We should use ``rtrim()`` instead of ``trim()``, because otherwise
(depending to the $delimiter/$before/$after) it's possible to remove
also something from the beginning of the $parents variable.
Fix warnings with WC_Order::get_item_total()

When calling WC_Order::get_item_total() for a fee, $item[‘qty’] is not
set which causes a notice and warning.
Fix query error when saving tax rates

Fixes #6202
Trigger event on order items save
Add `id` attribute to woocommerce_form_field args

This change allows developers to supply their own id attribute
when using the `woocommerce_form_field` template function.
The default ID is the escaped key, keeping the default behaviour.
Merge pull request #6201 from Ninos/template-breadcrumb

Template breadcrumb - only remove last category seperator
Merge pull request #6207 from tamarazuk/master

Trigger event on order items save
Merge pull request #6204 from om4james/issue-6202

Fix query error when saving tax rates
Merge pull request #6203 from maxrice/fix-order-get-item-total

Fix warnings with WC_Order::get_item_total()
Revise id, input_class and label_class escaping
Merge pull request #6208 from ragulka/form-field-id

Add `id` attribute to woocommerce_form_field args
JS min
wooconf plug on welcome screen.
Removing RC1 from version.
2.2 .pot file
Only display WooConf banner if WooConf hasn't happend yet.
Merge branch 'master' of github.com:woothemes/woocommerce
Fixed a small typo.
Display a backgroud color so text is readable while image loads.
fixed the order items qty calculation, closes #6209