add support for Markdown Extra Tables
Migrate table support as part of GFM support
add ability to escape |
merge upstream/master
Merge remote-tracking branch 'kitsonk/gfm_tables'

Conflicts:
	lib/marked.js
refactor table implementation.
fix misnested TH tags.
avoid using ES5 methods for tables.
fix gfm paragraph rule to account for tables.
optimize gfm tables. see --patience diff.
remove tabs in table output.
minor
whitespace output.
refactor again.
minor refactor.
refactor.
simplify table regexes. possibly use backreferences for leading whitespace.
major refactor.

Conflicts:
	lib/marked.js
refactor options.
small refactor.