Exporting a list and re-importing it doesn't always result in the same list

[picklesrus]

Expected Behavior

Scratch should be able to import all lists that it exports.

Actual Behavior

If a list starts with some characters (e.g. " and ,) Scratch exports a list it cannot then re-import.

Steps to Reproduce

1. Make a list that starts with a " (or a ,)
2. Add some more items
3. Export the list
4. Re-import the list
5. Notice that the lists are not the same

Also see related issue & discussion:
#4329
#4582

Operating System and Browser

All.

[Kouzeru]

It'd be more convenient having following options when a user trying to import/export data into/from list(s) in the context menu:

• Import .csv
• Export .csv
• Import .txt
• Export .txt

Both .csv options would import/export .csv(s) into/from list(s) according to CSV standards,
While .txt will import/export any text format file as plain text into/from list(s), leaving imported/exported data intact.