Added a Token Stream Patcher to retry parsing some strings as tokens.

* This class is an attempt to fixup the token stream to reparse
  strings as tokens that failed to parse in the tokenizer because
  of sol or other constraints OR because tags were being constructed
  in pieces or whatever.

* This is a pure hack to improve compatibility with the PHP parser
  given that we dont have a preprocessor.  This will be a grab-bag
  of heuristics and tricks to handle different scenarios.

* For now, the first trick in place is parsing "{|" after a newline
  as a table token.  This does a best-faith effort to also match
  attributes.  This trick is aware of nowiki nesting.

* Can add new tricks to this handler over time, if/as necessary.

* Parses (and RTs) the following wikitext correctly:
-------
{{echo|}}{| width = '100%'
|foo
|}
-------

* Surprisingly, 1 more wt2wt test green (it appears we did have
  a test case for this behavior).

* Also the following (among other such Wikipedia:* pages) parses and
  RTs with fewer errors than before:
  Wikipedia:Reference desk/Archives/Humanities/2007 August 13

Change-Id: Iddcae511cb5159ee21a337ee976559b7849fc160
Merge "Added a Token Stream Patcher to retry parsing some strings as tokens."