ApiRange corrections (#840)
ApiRange corrections (#840)

* Add SetStrikeout(isStrikeout) function for ApiRange

* Removing Unnecessary Instructions

* Some correction

* Code correction

* Method ReturnOldSelection() belonging to ApiRange has now become the ApiDocument method

* Errors correction

* Removed unnecessary function calls

* Added descriptions of ApiRange methods

* Some correction of descriptions
ONLYOFFICE/sdkjs,ONLYOFFICE/sdkjs,ONLYOFFICE/sdkjs,ONLYOFFICE/sdkjs,ONLYOFFICE/sdkjs