CodeCoverage is back

- BranchPoint processing is moved to OpenCover
- OpenCover exports new fileID SequencePoint XML attribute (and other)
- CodeCoverage adapted to exploit new XML attributes.
- CodeCoverage.Test adjusted to new situation.
- I certify that I own, and have sufficient rights to contribute, all source code and related material intended to be compiled or integrated with the source code for the #develop open source product (the "Contribution"). My Contribution is licensed under the MIT License.