Use line's styleref by default.
Fix Line\extraMetrics.

Use default argument and also fix align detection to not be stupidly
wrong.
Fix LineCollection\combineIdenticalLines.

Capitalization is hard.
.styleref should be .styleRef.

Make it consistent with every other usage in all the other files.
Use Line.align if extraMetrics has been run.

Fall back on styleRef.align, of course.