Call transfer function (Attended transfer) is now available in Web SDK

There are a lot of scenarios when you need to transfer a call to some other user or join it with another call by sending some command from a client built using Web SDK. New transferCall function enabled this functionality. It's rather simple function - just provide two call instances as its parameters and VoxImplant will try to join call1 with call2. If you want to know the result of the transfer you can add the following event listeners to call1 - VoxImplant.CallEvents.TransferComplete and VoxImplant.CallEvents.TransferFailed. If call was transferred successfully both call1 and call2 will be disconnected from Web SDK. In the world of telephony people usually call this function "Attended transfer".