Update docs with much simpler caching system.
Add docs for the timestamp behavior.
Add outline to counter cache docs.
Add docs for CounterCache.
Feeble attempt at proofreading.
Grammar fixes.
Fix formatting in migration guide.
Remove docs for classes that have been removed.
Add collections & validation docs to the TOC.
Fix build errors + missing files in TOC.
Move validation docs to live with other 'libraries'.
Fix more build errors.
Remove old model docs.
Remove sanitize docs.

Sanitize has been removed, update the docs.
Fix more broken links.
Additional fixes from review.
Merge pull request #991 from cakephp/3.0-timestamp-behavior

3.0 timestamp behavior
Merge pull request #989 from cakephp/3.0-query-cache

Update docs with much simpler caching system.
Documenting extract and reduce
documenting min()