replace locale with region

The locale is a combination of language and region.
wrap "To" in tc()

"To" is ambiguous and should be used with context
update transpations
require 5.6.1
update CHANGELOG
Merge pull request #30 from patrickheck/patch-1

replace locale with region
Merge pull request #31 from patrickheck/patch-2

wrap "To" in tc()
Merge pull request #32 from patrickheck/update-translation

update translations