Extract bitmap style serialization into shareable function to be used by `lineBitmapStyle`, too
Support bitmap pattern strokes for embedded shapes and in the Graphics API

Fully works, although the bitmap's position seems to be a bit off. That might be true for fills, too, though.
De-duplicate application of fill path in shape rendering

This is only two lines less code, but it reduces copy-and-paste code quite a bit.
De-duplicate application of stroke path in shape rendering

This actually fixes two bugs:
 - when starting gradient or bitmap line styles, a new path has to be started, as previous segments might have different styles, and would be re-stroked
 - when drawing clipping masks, all stroke path commands should just be skipped. Previously, only the actual `stroke()` call was skipped, nothing else. Quite unnecessary
Auto-close line paths, too, when auto-closing fills

Flash auto-closes shapes, but only if a fill style is defined.