Configure bisect repository through XML
Reimplement DepmapReader to use multiple threads

Reading depmaps is the dominant operation when running short-living
tools like xmvn-resolve or xmvn-subst.  Parallelizing the task of
reading and parsing depmaps should hopefully give a gignifficant speed
boost to these tools.
Read depmaps in DefaultResolver
Add scope to Artifact
Revert namespace changes in DependencyMap
Implement DefaultResolver using new repositories
Temporarly disable artifact blacklist
Don't try versioned paths when artifact is versionless
Merge repositories when merging configuration
Merge JavaHomeResolver into DefaultResolver
Remove obsolete resolvers
Turn DependencyMap into Plexus Component
Let Plexus initialize components