Changes for version 2.18
- Backport from bleadperl before 5.16.0 release
- base no longer sets a module's $VERSION to "-1" when a module it loads does not define a $VERSION.
- base no longer internally skips loading modules it has already loaded and instead relies on require to inspect %INC.
Modules
Establish an ISA relationship with base classes at compile time
compile-time class fields