With changes:

* update tests to pass (new encryption/encryption_key_id syntax).
* not merged the code that makes engine aware of the encryption mode
  (CRYPT_SCHEME_1_CBC, CRYPT_SCHEME_1_CTR, storing it on disk, etc),
  because now the encryption plugin is handling it.
* compression+encryption did not work in either branch before the
  merge - and it does not work after the merge. it might be more
  broken after the merge though - some of that code was not merged.
* page checksumming code was not moved (moving of page checksumming
  from fil_space_encrypt() to fil_space_decrypt was not merged).
* restored deleted lines in buf_page_get_frame(), otherwise
  innodb_scrub test failed.