[engine] Fix support for TargetMacros in the new parser, and support default names
Review Request #3966 - Created June 3, 2016 and submitted
TargetMacros support wrapping a Target constructor with additional logic: the underlying symbol they call needs to be replaced with a Registrar in order for it to be recorded.
There aren't any tests for TargetMacros at the moment, and I'm hoping that there might be a clean unification of context aware object factories and target macros via the new engine, so I've punted on adding them in favor of comparison testing for
./pants list contrib/go/examples/3rdparty::
- Capture objects created via the ParseContext inside a TargetMacro.
- Record TargetMacro aliases as aliases in the graph.
Remove wishful thinking.