A project that is not selected to build in the solution's configuration can not be built with BuildOnSave

[pragmatrix]

BuildOnSave should at least inform the user about why it can not build the project instead of producing an error messages like the following:

---------- BuildOnSave: Project: Web.Admin, Configuration: Debug Any CPU ----------
C:\Git\csharp\Cian.sln.metaproj : error MSB4057: The target "Web_Admin" does not exist in the project.
Done building project "Cian.sln" -- FAILED.
========== BuildOnSave: 0 succeeded, 0 failed ==========

See also #24.

[pragmatrix]

Beginning with commit 3945e4c, a notification is printed to the console.