Release v0.2.4

Improve support for debugging pogo-scripts in IDE:

• Add the dbg command (pogo --dbg myfile.php) which runs the script in a more debuggable way:
  • Launch in the require mode (which avoids extraneous subprocesses and preserves code-locations for breakpoints)
  • Place downloaded PHP assets in a folder adjacent to myfile.php
• composer subprocesses shouldn't use XDebug (unless they've opted-in)