[cmake-developers] Invalid/Reserved target names

[Nils Gladitz]

I would like to hijack/extend Stephen's changes in 
05f5fde0eb83c0e49aab3214f28a098861aa3313
to also disallow target names that have been implicitly reserved by some 
of the generators.

This list might not be complete but I assume it would be at least:
     all, help, clean, edit_cache, rebuild_cache, test, package, 
package_source, PACKAGE, ZERO_CHECK

Would anyone be opposed to this?
Could I extend the existing policy, should I create a new one or would 
it be ok without any policy even?

Nils