Psuedononymous main

Place the initial project file in project's base package, but keep the package declaration "main" so it remains executable.  This makes the created project behave more consistently with the expectations of `go install`; the project's executable name is now required to be the same as the name of the project's base package.

This also means `golink create` only requires one argument (the complete path of the base package), and `golink create` will no longer a package dir called main.

(Builds on top of changes from the "additional goad" branch.)