Add class level line coverage reports and line number reports for Jenkins.

Hi, I've added class-level coverage reports and line number reports.
These changes make Jenkins cobertura plugin happy.

Also I changed package-level function reports handling.
Originally these reports are combined into a file that was detected firstly.
However, reached/non-reached code annotation feature requires a corespondent source code.
So I've changed reports handling to generate package-level function reports each file.