Rename "Create Document" to "Create Sequence" and change labels

Modify the "Create Document" dialog as follows:

1. Change the dialog title to "Create Sequence".
2. Rename parameter "Document location:" to "Save sequence to file" (without ":").
3. Rename "Document format:" to "File format" (without ":").
4. Rename "Sequence name:" to "Sequence name" (without ":").