Added simple universal UncompressedVideoEncoder.

[bobahml]

A class for more convenient work with uncompressed data.

[baSSiLL]

My intention was that input format for all encoders is fixed to very popular BGR32, for simplicity of usage. However, I admit that sometimes it may be convenient to supply data in another format if you already have such bitmaps. What are your use cases for this new encoder?
Anyway, I think it's better to merge this functionality into existing UncompressedVideoEncoder rather than create another very similar encoder.

[bobahml]

I agree.
The new class is really better integrate with the existing ones.
My use case is simple - I get the uncompressed stream from the video camera (Basler): data come in the format of 8-bit grayscale and directly without compressing the stream writing to the output video file.
For me it is important that compression (or converting) is not performed.