Fix #539 Fixed error opening excel file created in encoding d… (#540)

* 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

1 files changed, 2 insertions, 6 deletions

diff --git a/file.go b/file.go
index 2e0d27b..d8f10fa 100644
--- a/file.go
+++ b/file.go
@@ -33,12 +33,8 @@ func NewFile() *File {
 	file["xl/styles.xml"] = []byte(XMLHeader + templateStyles)
 	file["xl/workbook.xml"] = []byte(XMLHeader + templateWorkbook)
 	file["[Content_Types].xml"] = []byte(XMLHeader + templateContentTypes)
-	f := &File{
-		sheetMap:   make(map[string]string),
-		Sheet:      make(map[string]*xlsxWorksheet),
-		SheetCount: 1,
-		XLSX:       file,
-	}
+	f := newFile()
+	f.SheetCount, f.XLSX = 1, file
 	f.CalcChain = f.calcChainReader()
 	f.Comments = make(map[string]*xlsxComments)
 	f.ContentTypes = f.contentTypesReader()