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 method returns the registry key
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\VisualStudio\<version>
A protected GetIDEVersion method retrieves the version-specific part of
the key name.