3.0 testcase

Some compatibility wrappers might still be useful, e.g. assertWithinMargin() or , as it simplifies asserts.
This improves readability.
But same are leftovers mainly from the SimpleUnit suite and are 100% redundant to the existing PHPUnit ones.

So removing

- assertEqual() in favor of assertEquals()
- assertNotEqual() in favor of assertNotEquals()
- assertIdentical() in favor of assertSame()
- assertNotIdentical() in favor of assertNotSame()
- assertPattern() in favor of assertRegExp()
- assertNoPattern() in favor of assertNotRegExp()
- assertReference() if favor of assertSame()
- assertIsA() in favor of assertInstanceOf()

Note:
My [Upgrade shell task for tests](https://github.com/dereuromark/upgrade/blob/master/Console/Command/UpgradeShell.php#L867) contains those replacements.
Maybe we can add this in as an improved version (doesn't check for message param yet) for the 3.x upgrade shell?