Refactoring, Bug Fix and Rebuild All Stubs

* NuGet: Improve the error handling to hide unneeded error messages for developer under normal conditions. In addition, did refactoring - organized some function names, enhanced the type check for the arguments of some functions.
* NuGet: Fixed #16: Nested Type can't be resolved in its indirection stub. => Naming convention was insufficiency. Also it was problem that full name wasn't specified as described by Issue's comment, but it was real problem that the name of a nested type wasn't generated correctly.
* NuGet: Fixed #17: Prig can't uninstall correctly against the solution that contains multiple test projects. => It wasn't implemented. Added the check whether the test projects that are installed Prig are around one to Install.ps1/Uninstall.ps1.
* All: Re-generated all indirection stubs, because the stub content is changed to correct the issues #16, #17.