The two pixels in TextOffset is a magic number and not PPI scaled

[pyscripter]

SynEdit leaves two pixels between the Gutter and the text unused and painted by the editor background. It is used in the calculation of fTextOffset and other places.
The number of 2 is hardcoded (magic number) and not PPI scaled.
Make it a field and PPI scale it.

[pyscripter]

Introduce TextMargin property (not published) PPI scaled. Could consider publishing it. It gives the distance in pixels between the Gutter and the editor text.
Changed its value to 3. I think it looks better with 3 than 2.