Drop all DefineProperty calls for non-chained properties. Drop the
documentation from the chained ones. The documentation for all
properties is now in Help/prop_*/*.rst files.
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 teaches the define_property command signature to accept multiple
arguments after the BRIEF_DOCS and FULL_DOCS keywords. We append the
arguments together, making specification of long documentation easier.
Brad King
Ken Martin