This converts the CMake license to a pure 3-clause OSI-approved BSD
License. We drop the previous license clause requiring modified
versions to be plainly marked. We also update the CMake copyright to
cover the full development time range.
This adds the OPTIONAL option to the install(DIRECTORY) command. It
tells the installation rule that it is not an error if the source
directory does not exist. See issue #8394.
-move std::string Destination to cmInstallGenerator, since all (except
the script one) have it and add a const accessor so it can be queried
-use temporary variables in cmInstallCommand for the generators so they can be reused easier
-some more const
Alex
