Fixed step to skip generated functions

Changed cmd_step to check at onBeginInterrupt if the file line is empty i.e. returns as ":0"
In this case continue stepping

Reviewed By: @mikemag

Differential Revision: D1017420
Fix list command so that it finds the right start line and it can find systemlib.php

The list command was using the the string "line2", cunningly disguised as the static string variable 'line1' to look for the line where a func/class/method starts. Also, the file name it got for systemlib.php was expected to always be exactly "systemlib.php" but it turns out this is no longer the case, or at least not always.

Reviewed By: @mikemag

Differential Revision: D1018535