Redesigned model cache to be more reusable.
Merge pull request #71 from PiranhaCMS/cache-redesign

Redesigned model cache to be more reusable.
Some portability fixes.
Merge pull request #72 from PiranhaCMS/portability-fixes

Some portability fixes.
Added validations when adding regions & properties.
Merge pull request #73 from PiranhaCMS/pagetype-validation

Added validations when adding regions & properties.