Check code for errors and warning

[AydinHassan]

A users solution may trigger errors and warnings. This would be contained in the output and would obviously fail the StdOutCheck. However, could we provide more meaningful feedback?

PhpErrorCheck

• We could grep the output for PHP Notice: and PHP Warning. This seems a bit flaky as that could be valid output.
• We could lint the file first, check if it's valid PHP code, then parse the file and add in some code, like an error-handler which would exit with a non-zero error code.