Call a writer to dump html; new warning patterns.

* HTML emit functions now take a writer parameter.
  This makes warn_common.py one step closer to the ChromeOS version.
* Add new found warning patterns from java and yacc.

Test: warn.py --url=http://cs/android --separator='?l=' build.log > warnings.html
Test: warn.py --gencsv build.log > warnings.csv
Change-Id: I5c446ca767746598f07603591fdf98f7d82cae17