Run python with -E flag.

This ignores a PYTHONPATH the user has lying around for some other reason.
Edit all no longer opens TL files.
Style _default for the Japanese translation.
Delete obsolete scripts.
The after checkout script can now copy the files necessary to run
Ren'Py from a built Ren'Py.
Add a README that shows up on github.
Restart interaction on FieldValue change. Add VariableValue.
Fix translation documentation problems reported by Koichi.
Change the console activation key to shift+O only.

The backtick key invokes IMEs, which can confuse Ren'Py.
Implement config.console_callback.
Add load and save commands to the console.
merge with trunk
update translation template