Fix T commands following q or t in paths

Fix Kozea#170.

Author: liZe

cairosvg/path.py

@@ -408,10 +408,12 @@ def path(surface, node):
             if last_letter not in 'QqTt':
                 x2, y2, x3, y3 = abs_x, abs_y, abs_x, abs_y
             elif last_letter in 'qt':
-                x2 += x1
-                y2 += y1
-            x2 = 2 * abs_x - x2
-            y2 = 2 * abs_y - y2
+                x2 += abs_x
+                y2 += abs_y
+                x3 += abs_x
+                y3 += abs_y
+            x2 = x3 + (x3 - x2)
+            y2 = y3 + (y3 - y2)
             x1, y1 = abs_x, abs_y
             x3, y3, string = point(surface, string)
             xq1, yq1, xq2, yq2, xq3, yq3 = quadratic_points(