Add an option to specify preferred locale (en-US, zh-CN, etc.)

[DrewNaylor]

This is something I've been thinking about doing for a while and only decided to just write it down. This option will be in the Options window under the Package List + Details tab, and it can probably be a dropdown with the default being to use whatever the defaultManifest value is. Wait, or make it a checkbox that, if checked, will let a non-exhaustive list (not sure if it would be possible to list them all, because there are so many different possible locales) of example locales be displayed and whatever the user prefers to use to be typed in. If the locale they type or select isn't available for a package, then it'll just use the defaultLocale field.

Maybe the default item can be the language their Windows install is in. Then, resetting to defaults will load their Windows locale and the option I type in the config file can just be unset-UNSET so the program knows to check Windows instead.