Support emojis, files, and images

[colbytimmsl]

After some testing I realised that you can't send emojis, images, or files to the receiving user. Would be great to see this added as a feature. Currently if a user sends any of the above mentioned features, the receiver will get a blank message.

[tbuha]

From the source code I can see that it supports only text messages.
It requires changes in the MessageRouter class.
And it is possible to override method RouteMessageIfSenderIsConnectedAsync

line 420

[tbuha]

@colbytimmsl
I've created simple method extension to send image/file messages

tbuha@b43075a