Improved Generator Performance and Continuous Send Mode

The highlight of this release is a significant performance boost in the Generator tab. You can now work more fluently with large number of messages and, therefore, perform more powerful fuzzing attacks. Hack that stuff!

If you have a large number of messages to send that can not be premodulated at once, URH will send them in a new continuous mode. This means all messages are modulated live during sending so the actual RAM usage stays low.

fixed issues in this release:

• fix #242 - improved performance for many messages e.g. produced by fuzzing a 16 bit label
• fix #248 - enhancements of file tree
• fix #269 - Add "add empty message" action to context menu in generator table