temporary FIX: drawToPMCanvas -> dpi ignored

[radjkarl]

Hi there,

when creating a raster image from an SVG with dpi values different then 72, the image range is scaled, but not the image itself.

Version used: 0.8.1

Minimum working example:

`
import numpy as np
from lxml import etree
from svglib.svglib import SvgRenderer
from reportlab.graphics import renderPM
import pylab as plt

s = ''' <svg
xmlns:dc="http://purl.org/dc/elements/1.1/"
xmlns:cc="http://creativecommons.org/ns#"
xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
xmlns:svg="http://www.w3.org/2000/svg"
xmlns="http://www.w3.org/2000/svg"
xmlns:xlink="http://www.w3.org/1999/xlink"
version="1.1"

width="100mm"
height="100mm" >

aaaaa
bbb
'''.encode('UTF-8')

parser = etree.XMLParser(remove_comments=True, recover=True)
xml = etree.fromstring(s, parser=parser)

for dpi in (72, 150, 300):
drw = SvgRenderer('_tempfile.svg').render(xml)
pil = renderPM.drawToPIL(drw, dpi=dpi)
plt.figure(dpi)
plt.imshow(np.array(pil))
plt.show()
`

This generated the following output:

Output after fix:

I am sure that there is a better way ... such as incorporating d.renderScale (in renderScaledDrawing) right