Ability to use XDEBUG on tests

[jayhealey]

In order to improve the debugging Codeception tests as they run, it'd be useful to add a new configuration option to Webception for the XDEBUG_CONFIG idekey. The Webception UI will include an additional option to set the config before running the tests.

XDEBUG_CONFIG=“idekey=netbeans-xdebug" vendor/bin/codecept run --config=“"

Thanks to Jeremy Coates (@phpcodemonkey) for the idea and example implementation.