ENH: Further cleanup of installation script generation.  The per-component and per-configuration testing is now done in cmake code instead of in the FILE(INSTALL) command.  The generation of the cmake code to do these tests is centralized in cmInstallGenerator.  Old-style shared library versioning and component/config support code has been removed from FILE(INSTALL).  This commit is surrounded by the tags CMake-InstallGeneratorCleanup2-pre and CMake-InstallGeneratorCleanup2-post.