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 introduces a new syntax called "generator expressions" to the test
COMMAND option of the add_test(NAME) command mode. These expressions
have a syntax like $<TARGET_FILE:mytarget> and are evaluated during
build system generation. This syntax allows per-configuration target
output files to be referenced in test commands and arguments.
