tests for gfm tables
created MarkdownExtra class
Merge branch 'master' into markdown-extra

* master: (43 commits)
  fixes #45 wrong parsing of text before headlines
  small code enhancements
  simplified parser
  allow using link parsing method in subclasses
  added tests
  added support for simple references
  improved patterns
  more tests on code
  fixed some issues with code blocks
  more url tests
  even more sophisticated url patterns
  Update README.md
  Added extensions section to readme
  do not include ending punctation in URLs
  Update README.md
  added testcase
  adjusted testcase
  added test case
  phpdoc
  Excessive variables declaring/setting removed.
  ...

Conflicts:
	phpunit.xml.dist
implemented markdown extra attributes
markdown extra special attributes on code blocks
added context information to the parser

fixes #47, fixes #48
Markdown Extra tables
Merge branch 'gfm-tables' into markdown-extra

* gfm-tables:
  tests for gfm tables
finished table support for GFM and markdown Extra
Merge branch 'markdown-extra'

* markdown-extra:
  finished table support for GFM and markdown Extra
  Markdown Extra tables
  added context information to the parser
  markdown extra special attributes on code blocks
  implemented markdown extra attributes
  created MarkdownExtra class
  tests for gfm tables

Conflicts:
	Parser.php
	phpunit.xml.dist