Revision 644354

Fixing MNG-3355 and MNG-2339.

This commit introduces three changes: user-level properties that are separated from the execution properties, where execution properties contain envars, sysprops, and user-level properties...user-level properties are useful for POM interpolation for 2339 and 3355.

Second, a ProjectBuilderConfiguration interface and default implementation, to stem the proliferation of method parameters to projectBuilder methods. This was a natural place to introduce it, as user-level properties had to be passed in separately from the execution properties, for interpolation.

Finally, interpolation has been switched to use the new plexus-interpolation project, which is based on the classes in plexus-utils.