[Rd] bug in fix & edit (PR#7642)

[roberts at berkeley.edu]

The edit command (and the fix command, which calls edit), when used on data frames, cause a character variable to become a factor variable. Here is an example:

>> is.factor(work$notes)
>[1] FALSE
>> is.character(work$notes)
>[1] TRUE
>> fix(work)
>> is.character(work$notes)
>[1] FALSE
>> is.factor(work$notes)
>[1] TRUE

in this example, no editing was done -- the data frame work was not changed by the user.