Add leading

[vonloxley]

It would be nice to get some leading between the lines. I used the following to get a line-height of 150%:

textsize = draw.multiline_textsize(text, font=im_font, spacing=kwargs['font_size']//2)

draw.multiline_text(offset, text, (0), font=im_font, align=kwargs['align'], spacing=kwargs['font_size']//2)