Check presence of main.py during build time

[dessant]

From @miohtama on February 26, 2016 21:24

Now it is possible to create an APK without a valid Python entry point. In this case the application just quickly flashes, then closes.

If the developer makes a mistake with packaging and main.py doesn't end up in the APK the application startup does not give any meaningful error message. For novice users it might be difficult to spot the error from adb logs.

[dessant]

This should probably be addressed in p4a directly.

[dessant]

From @miohtama on February 26, 2016 22:39

Gotcha. Please point me forward to another project if this a wrong issue tracker.

[dessant]

I'll port it for you. 😉

[inclement]

This would be fixed by #698.