[fpc-pascal] Request to make TJSONStreamer.StreamProperty virtual

[Hairy Pixels]

For the JSON RPC library I wanted to supported dynamic arrays but in order to do this I needed to duplicate TJSONStreamer's ObjectToJSON  and StreamProperty in order to bypass some exceptions. If StreamProperty was virtual I could simply override that and stream the dynamic arrays before calling inherited. 

What do you think about that?

Regards,
	Ryan Joseph