Method to render a formula to an existing bitmap

[WhiteBlackGoose]

Motivation

To avoid reallocations for every created bitmap. Useful, when rendering a formula for the same control/file.

Details

Proposed syntax for TexRenderer:

public void RenderToBitmap(RenderTargetBitmap dst, double x, double y)

The idea is to render it to the given bitmap of type RenderTargetBitmap. Because the rendered image has an unpredictable size, I suggest resizing it internally to the size of the destination bitmap.