iecorrect: move the "other" functionality to a new command

[luizaandrade]

From Stata Journal reviewer:

In general, I don’t like these other options. First, its functionality isn’t what I initially thought after reading the explanation in your article. To me, it sounded like it was to make corrections to factor variables, but in fact you can do that with the numeric sheet and it works just fine. I think this sheet is to change the labels of a factor variable? But it assumes you still have the string variable in your dataset; I’m not sure this will always be the case. If you could make it work without requiring a stringvar I think that would be more useful.
I also don’t like that you have to specify other, first to add that sheet to your template and then to implement those changes. Perhaps the authors have a good reason for this. The case I am worried about is what if you don’t initially specify other when creating the template, make a bunch of changes, and then later realize you want to make changes to factor labels, as well. Can you add this sheet to an existing file? And again, I could think that I have implemented all the changes and not realize that the changes in the other spreadsheet weren’t implemented, so having a way to mark which changes were implemented would be useful.