Prepend main WC Session cookie with 'wp' so batcache doesn't cache pages, and set cookie only when cart has contents. #3513
Wrap messages with WC div so they are styled
Unused vars Closes #3937
Some fixes for Czech translation

* Close HTML tags correctly
* Fix the plural forms expression
* Remove excess placeholder
Merge pull request #3943 from SergeyBiryukov/master

Some fixes for Czech translation