#73 support for method level coverage

[Troy Schulz]

I have:
- added methods to the CoverageData interface to support method level statistics, matching the pattern already in place for branches and lines
- implemented above methods where needed
- added generation of method coverage to html report
- added generation of method-rate attribute to xml report. (however it is commented out so the tests pass)
- updated PackageDataTest and ClassDataTest to test new method coverage methods

Since the DTD is on sourceforge, a new version, presumably 'cobertura-04.dtd' would need to be created that adds the new 'method-rate' attribute and the XmlReport class would need to be modified to uncomment the 3 lines that print out the 'method-rate' for the applicable tags.

If something is incomplete or I can be of any other help, just let me know.

[Troy Schulz]

Patch file for method covarage statistics.