CLN/ENH: add parse_dates arg and use TextReader
ENH: add tupleize_cols, thousands args

tupleize_cols=False by default, for back compat
thousands=',' by default, because we're not parsing CSV
TST: add test case for GH5048

Parsing headers of non-string columns
TST: add nyse wsj test
CLN: proper parse_dates support
Merge pull request #4770 from cpcloud/read-html-refactor

REF/BUG/ENH/API: refactor read_html to use TextParser