title: Remove AddIn path from UDF in Excel formula
body: <p>My addin was xla, now I use excelDNA, so it becomes xll, 
  When I open spreadsheet built in previous version of My addin, 
  for the UDF, it shows myUDF with path of xla. e.g "C:\Program Files\Installation folder\MyUDFs.xla!MyUDF", 
  when I click Edit link and change source to "C:...\MyUDFs.xll"
  I got a pop up which says 
  "Excel cannot update one or more links in this workbook. To update the links, open all the link source files(click Edit Links on the Data tab).
  To be sure all calculations are updated. press F9"
  I click OK, then the path of MyUDF changes from xla to xll, e.g. C:\Program Files\Installation folder\MyUDFs.xll!MyUDF
  For clients, this will break all their spreadsheets (could be 100+) built in previous version.
  I know I can write a VBA code to remove paths from all MyUDF. but it is not ideal since users have to open up spreadsheet and put the code in spreadsheet and run. </p>
  
  <p>I wonder if there is a better/more convenient way for clients to solve the issue
  thanks </p>