symmetric delimiters, fix safe-paths references
fully-compliance AsciiDoc table support (psv, dsv, csv)

- classes to manage table content
- parser method for processing table content
- support for nested tables
- support for tables containing a nested AsciiDoc document
- table templates for HTML5 and DocBook45
- constant for default docbook page width
- optimization for matching any block
- rename :title regex to :blk_title
- change option attributes from foo-option to option-foo
- convenience method for checking for block title
- various compliance fixes
- let literal block masquerade as listing block
- require [source] block attribute to treat listing as source code
- don't clobber custom authorinitials
- additional method on test_helper to perform css assertions
- additional method on test_helper to retrieve xml node for xpath or css