Move the Version member to the top cmLocalVisualStudioGenerator class
and set it consistently for instances created by all the global
generator versions. Use an enumeration type with values scaled by a
factor of 10 so we can handle VS 7.1 without out-of-order numbers.
VS 7.1 support for SuppressStartupBanner was broken by commit 25116a3c
(Fix CMAKE_VERBOSE_MAKEFILE for VS10 vcxproj files, 2011-10-11) because
it assumed comparison of VS version numbers works. Now it does.
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.