supports tables in lists like github

Not sure how often anyone tries to do this other than me, and maybe it is a sign I need to simplify my writing, but github supports tables in lists so here is simple patch plus tests so marked does too.

For example:

* a list
* table in list

  | Weee |
  | ------ |
  | I'm in a list |

| Awwww |
| ------ |
| Not in a list |


Thanks for looking and thanks for marked.