karo.checkWhether checks for attributes also

So, karo.checkWhether a, 'x' will return true if
  1. $(a).hasClass 'x' OR
  2. $(a).attr(x) is 'true'
Tightened logic for setting class and other attributes on left-tabs

The code is fugly. But it seems to work
Bug fix in method honest?
General bug fixes and enhancements