Save/auto-save does not work with "Reverse Complement" / "To Upper" / "To Lower" / "Use Feature Library"

[zhanxjx]

EDIT: after further examination, I found this bug only exists if a chunk of the file is deleted with right click->delete, so if you fix #110 , this should also be resolved, I believe #97 is also related to this bug.

Currently, after changing the sequence (either delete or add some stuff), when "Use Feature Library" is clicked, all the changes will be discarded and the file content shows up randomly.

1. Open a file
   
2. Modify it
   
3. (Optional) Click "Save", or wait for sometime to auto-save
4. Click "Reverse Complement" / "To Upper" / "To Lower" / "Use Feature Library"
   

cs169test

[zmbush]

Right click and delete is NOT a correct way to delete text.