Load modernizr.js in header, so IE8 can style HTML5 elements. Remove IE specific CSS

See: https://github.com/fisharebest/webtrees/commit/9c8d54960d7d36c8862c2fb7597389eaa888ac92 and https://github.com/fisharebest/webtrees/commit/2eaa2f9bb47661cb654bdb4f83fdae1144e3107b
Whitespace
Use semantic markup in header and add link to tree title.
Coding standards formatting