[Lazarus] TImage drag of big image

[AlexeyT]

I want to add to TImage props: a) enable drag of pic, when pic is too 
big or zoomed. Eg if pic is 1000x2000 and TImage is 300x400. b) key 
modified (e.g. Ctrl or Alt) with m-wheel - to zoom pic in/out. c) prop 
ZoomValue to set/get zoom in %.

Such patch can be accepted?

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Regards,
Alexey