Added possibility to insert or duplicate many rows at once.

Added a new field "Inset N times" to the insert\duplicate page. That brings possibility to change many rows at once (usefull when you need to populate database with test rows fast).
![snapshot-4](https://cloud.githubusercontent.com/assets/635848/2763363/a9029a76-ca02-11e3-9c58-f735f3452554.png)