* Fixed issue #539 Fixed error opening excel file created in encoding different from UTF-8, added logging of possible errors when decoding XML if the function does not provide exit with an error
* Added test for CharsetReader
* Fixed #discussion_r359397878
Discussion: https://github.com/360EntSecGroup-Skylar/excelize/pull/540#discussion_r359397878
* Fixed go fmt
* go mod tidy and removed unused imports
* The code has been refactored
Alex Geer