make text-decoration inherited, this is closer to the actual behavior than not inheriting

Ignore-this: 880be2c400ec464cb448330096ee0f7f

darcs-hash:20140909175754-fae1a-6b8fa7ef577393b4c98494e8f451d5920d9f24f8
make underlines have shadows too, done by making it possible to have runs of several layers

Ignore-this: f9f8a3cea3b2d31d658a9eb7efb218db

darcs-hash:20140909183846-fae1a-7acc4949e830cffa82f9836c53737022b9cdc03a