Lookup the Intel VS plugin version on demand in the VS global generator,
compute the corresponding .vfproj format version number, and memoize it.
Add it as a CMAKE_VS_INTEL_Fortran_PROJECT_VERSION platform definition.
Generator expressions are supported in many places and are a distinct
concept worthy of their own manual page. The old builtin documentation
was previously represented by preprocessor macros to generate it into
each place that supports them. Factor out the duplicate content into a
dedicated cmake-generator-expressions manual page and reference it from
each original location.
Brad King
Kitware Robot