Minor change to actually cover the case where a line segment doe not point into the same direction.

Also increases coverage by explicitly optimizing a lineto command (instead of only "implicit lineto", i.e. effectively moveto, commands)

testscour.py

@@ -1240,7 +1240,7 @@ class CollapseStraightPathSegments(unittest.TestCase):
                               'm0 0h10 20',
                               'm0 0h10 20',
                               'm0 0h10 20',
-                              'm0 0 20 40',
+                              'm0 0 20 40v1l10 20',
                               'm0 0 10 10-20-20 10 10-20-20',
                               'm0 0 1 2m1 2 2 4m1 2 2 4',
                               'm6.3228 7.1547 81.198 45.258']

unittests/collapse-straight-path-segments.svg

@@ -21,8 +21,9 @@
  <path d="m0 0h10 20" style="marker:url(#dot)"/>
  <path d="m0 0h10 20" style="marker-mid:url(#dot)"/>
 
- <!-- all lineto commands should be collapsed into a single (implicit if possible) lineto command -->
+ <!-- all consecutive lineto commands pointing into the sam direction
- <path d="m 0 0 l 10 20 0.25 0.5 l 0.75 1.5 l 5 10 0.2 0.4 l 3 6 0.8 1.6"/>
+      should be collapsed into a single (implicit if possible) lineto command -->
+ <path d="m 0 0 l 10 20 0.25 0.5 l 0.75 1.5 l 5 10 0.2 0.4 l 3 6 0.8 1.6 l 0 1 l 1 2 9 18"/>
  <!-- must not be collapsed (same slope, but different direction) -->
  <path d="m 0 0 10 10 -20 -20 l 10 10 -20 -20"/>
  <!-- first parameter pair of a moveto subpath must not be collapsed as it's not drawn on canvas -->