more spec examples tests. fixes #419, #420, #421, #422
added tests for examples 10+11 (fixes #423, #424), updated spec example #'s to match new draft
updated spec links to latest TR LCWD, removed prefixes, fixed some asserts
updated clip-path circle syntax
removed test for attr() since it's at risk and not really about shapes
fixed reftest + self describing statement
removed prefix
fixed circle clip-path syntax
fixed reftest
create new ref file for border, padding, and content box tests - margin box is calculated differently, a ref file can't be shared
fixed ellipse clip-path syntax
removed prefix
Merge pull request #507 from rhauck/pr-436-branch-copy

Pr 436 branch copy