Append an item[is_new3ds] to config file[System] group

Implement APT::SetNSStateField,it will update the unknown NS_state_field

This also means : we have only one config file, now

- Config: Add an option for selecting to use shader JIT or interpreter.
- Qt: Add a menu option for enabling/disabling the shader JIT.

Changing it makes emulation inherently inaccurate. It also had a wrong
default value (30, whereas the real system has a refresh rate of 60 Hz)
which, even if changed, would continue to be used unless people manually
removed it from their config files.

The background color can be seen at the sides of the bottom screen or when the window is wider than normal.

Before, it used to use whether the directory actually existed. As a result, .citra-emu/sdmc was never auto-created (something quite confusing to me until I read through the logs).

Uses QSettings on citra-qt, and inih on citra-cli.