Add support for signals with return values to DynamicSignal.cs
Submitted by whe..@..il.com
Link to original bug (#749573)
Description
Currently gst-sharp only supports signals that should not return any value (the Connect-method only accepts delegates with return-type void), whereas when registering for rtprtxsend/rtprtxreceive on the RtpBin (with the "request-aux-receiver"/"request-aux-sender"-signals) a GstElement needs to be returned (the AUX-element). This means that the functionality of retransmission currently is not supported in gst-sharp.