New Feature: Indirectly Call for One Runtime Instance

* All: Modify README.md according to new API, and fix typo.
* All: About the generated stubs, equalized their class name and file name. Because the file name didn't have the prefix `P`.
* All: Added the dependency information for the external library to generate T4 on every build time. For more information, please see this help: [Code Generation in a Build Process](http://msdn.microsoft.com/en-us/library/ee847423.aspx)
* NuGet: [NOTICE] Changed the generated stub's API. It became a static method from a nested type. For example, until previous, the stub against `System.DateTime.Now` was `System.Prig.PDateTime.NowGet.Body`. From now, the stub becomes `System.Prig.PDateTime.NowGet().Body`. Because the previous version can't propagate an instance.
* NuGet: Supported the feature to generate the stub for one runtime instance.
* NuGet: Fixed #6: Methods defined in `.exe` can't be called indirectly. => It was the infrastructure's bug. For more details, please see [Swathe's commits](https://github.com/urasandesu/Swathe/commits/master).
* NuGet: Fixed #7: Path to `tools` become unreachable from the Package Manager Console after building a project. => I think this is NuGet's bug... :( Unfortunately, there is nothing for it except to modify Prig, so added the command `prig` to wrap `prig.exe`.
* NuGet: Fixed #8: Against the method that contains a nested type, indirection stub can't be created. => Nested types have the property `IsNestedPublic` to indicate its openness in isolation from `IsPublic`. I merged to use it.
* Framework: T4-nized `IndirectionDelegates`. Until previous, they were generated by my hand ;)