This makes it possible to use enums as the config type.
Default values are now clearer and there's no need for casts
when calling Config::Get/Set anymore.
In order to add support for enums, the common code was updated to
handle enums by using the underlying type when loading/saving settings.
A copy constructor is also provided for conversions from
`ConfigInfo<Enum>` to `ConfigInfo<underlying_type<Enum>>`
so that enum settings can still easily work with code that doesn't care
about the actual enum values (like Graphics{Choice,Radio} in DolphinQt2
which only treat the setting as an integer).
This excludes the second argument from template deduction.
Otherwise, it is required to manually cast the second argument to
the ConfigInfo type (because implicit conversions won't work).
e.g. to set the value for a ConfigInfo<std::string> from a string
literal, you'd need a ugly `std::string("yourstring")`.
Changes:
- `ShowDevelopmentWarning` is now under the '[Interface]' group in
Dolphin.ini, with other interface-related settings. So, whoever uses
DolphinQt will have to edit that manually again. Sorry!
- Game search paths and the last file are now shared properly with
DolphinWX
- Qt-only preferences like "Preferred View: list/table" are now
stored using the platform's native settings storage, rather than in
UI.ini
