more simplify bugs

more simplify bugs

SkOpAngle::alignmentSameSide()
Shifting an edge to align it for angle sorting may move a compared edge to the opposite side.
For lines that are shifted, check to see if this is so.

class SkOpContourBuilder
If the path contains a pair of lines that cancel, skip them as early as possible.
While not strictly necessary, this optimization is cheap and makes debugging much easier.

SkOpEdgeBuilder::walk()
  case SkPath::kCubic_Verb:
If max curvature or inflections break a cubic into pieces, make sure that the pieces are
large enough to process. If not, add the broken piece back to a neighbor.

Correct debugging that had gone stale.
Add active span debugging cache so only changes are shown.

TBR=reed@google.com
BUG=skia:6401

Change-Id: I766f77e4fb9b76537cf5464961addb103114f5db
Reviewed-on: https://skia-review.googlesource.com/5764
Reviewed-by: Cary Clark <caryclark@google.com>
Commit-Queue: Cary Clark <caryclark@google.com>