Add Cache::get_handler()

To try and fix compatibility issues, add Cache::get_handler() This is now called instead of Cache::create(), *except* if the cache handler is registered via the legacy method.
Throw a E_USER_DEPRECATED error on old cache method
Merge pull request #221 from rapid2k1/master

Split some long one liners in the demo into multiple lines. Fixes #191
Add tests for Cache classes

This should ensure that the correct methods are called.
Blacklist rather than whitelist for Travis
Merge branch 'master' of github.com:simplepie/simplepie
Merge branch 'master' into cache-backwards-compat
Ignore E_NOTICE too

Apparently, this throws a notice, not a deprecated error. Who knew.
Add CacheTest to AllTests
Rather than changing error_reporting, just suppress

Hopefully this should fix tests on 5.4
Merge pull request #243 from simplepie/cache-backwards-compat

Fix backwards compatibility with cache subclasses
Remove unneeded class for CacheTest
Generate an error if DOMDocument doesn't exist

Rather than trying to load the class and getting a failure, this much more
sensibly generates an error. Fixes #241

Also introduces SimplePie_Exception, which is only used internally.
Add SimplePie_Exception

This is only used internally at the moment. It may be exposed in the future.
Ensure the updated date is fetched correctly

Fixes #239, thanks to @poluxus
Ensure $link->getLineNo() exists before using

Fixes #223
Ensure "this should never happen" doesn't

Fixes #219
Fix cache testing bug
Re-add the deprecated get_/set_favicon()

These shouldn't have been removed without deprecating them. Instead, use
an external service to handle all of that for us, and throw deprecated
errors when people try to use them.
Ensure that constructor passing still works

Deprecate, rather than remove. This should work in a
backwards-compatible way.