Remove obsolete line from AnalyzedPHPFileTest
Simplify PHPShortTagsTest
Move redundant boilerplate from tests to a common parent class

This includes all tests except for AnalyzedPHPFileTest, BaseScannerTest,
and VIPInitCheckTest, which are a bit more complex. Also, JavaScriptLintTest
and VIPParametersTest could use some more optimization, possibly requiring
some extra parameters or logic in CheckTestBase::runCheck().
Fix malformed PHP in the AnalyzedPHPFileTest

These occurrences cannot be really parsed by the PHP interpreter,
which would break the test if a more compliant PHP parser was used.
Update the WidgetsTest class to extend the new CheckTestBase class.
Include additional boilerplate in the unit test for register_widget() to be sure the error being tested isn't related to other widget issues.
Update the unit test checking for register_widget in function names to include additional variations.
Use regex to reduce false positives in the check for register_widget().