* Data escaped and validated. Plus translator comment documentation added.
* If it should be int then we should change the empty string default parameter to 0 as in 'if' condition checking 0 and empty string are same.
* Extra bracket removed.
* Indentation is fixed now.
* The taxonomy object should not be assigned to a variable before checking if this is a taxonomy or not.
* echo esc_attr__ replaced by esc_attr_e and visually tested.
* As I use WordPress VIP Coding Standard, they were marking them as warnings. But now it's fixed again.
* Escaping fix
* Extra Bracket Fix Again
The single translation string `by` is not easy to translate without a context. In this case, using the context function `_x()` is not the best solution.
A better way would be to create two complete translation strings for refund with a user and without a user.
* use %s in translations strings
* merge simmilar error strings
* i18n: use sprintf() in translation strings to make them easier to understand for translators
* i18n: remove sprintf() function from translation string with unused parameter
* i18n: move colons and brackets into the translation strings
* revert comit addaa5d
* Fix broken sprintf()
* i18n: move colons into the translation strings on error messages
* Fix Travis-CI Error: operator must be surrounded by a single space