Add "configure script" (WIP)

[petabyt]

• Python script that checks system dependencies
• Helps avoid random bugs, avoids mysterious errors
• rst2html, pip2, python2, arm gcc correct version, bash, host gcc
• Spews a lot of garbage output in console currently

Any suggestions welcome, I hardly understand the ML build system.

[petabyt]

Configure scripts in Python seem to be common: https://github.com/ninja-build/ninja/blob/master/configure.py

[petabyt]

Updated, still doesn't test modules. Don't think it's a big deal though, it's mostly standard library packages right?

[reticulatedpines]

This has stalled I think, and the build system has changed significantly since then, anyway - no longer needs python2.