Removing unnecessary unset in Cache::read.
Better isolate file cache adapter test with clear.
Adding missing properties on test class.
Making $data parameter required in Set::matches.

Refs #993.

This has been a leftover of a previous refactor (9084d697).
This patch changes signature as per documentation.

It can be expected that as the second parameter must be given, the first
must also always be given, so this doesn't break BC.
Merge pull request #1046 from davidpersson/cache-multi

Homogenization of multi-key support in Cache
Refactoring, documenting and fixing read-through caching.

Adding tests.
Fixes #889.
Adding integration test for read-through caching.

Proves #890 has been fixed by prior changes from PR #1046.

Closes #890.
Consistently implement alternative cache expiration.

All the following BC Breaks are only relavant if you've been relying on
prior unsupported and undocumented functionality.

Closes #1022.

Adding tests.

Refactoring setting of TTL in redis cache adapter.

BC Break: APC adapter would previously would alternatively take
a timestamp as the future expiration time. Passed integers are now
used as the TTL in seconds.

Please update your code accordingly when using the apc cache adapter
in combination with integer expiry.

BC Break: When using an integer expiry with the Memcache adapter it
was passed unmodified to the underlying driver and could be inter-
preted as either a TTL or an absolute timestamp. Passed integers are now
always used as the TTL in seconds.

Please update your code accordingly when using the memache cache adapter
in combination with integer expiry.

Removing unsed.
Refactoring write method in redis cache adapter.
Use transactions in write of redis cache adapter.
Increasing sleep; to fix time-dependent cache tests.
Fixing unfinished redis cache adapter write method.
Handle double no expiry in all cache adapters.

Adding no expiration capabilities to file adapter.

Adding tests.