Date.php: Silently fall back to en when the locale isn't supported

[zhaofengli]

Currently, a fatal error occurs when the program tries to setLocale() to an unsupported one (e.g. ta). Maybe we should silently fall back to en in such situation.

[danhunsaker]

I think I'd prefer to have a non-fatal Exception in this case, to alert me that the locale isn't available during development. It'd be better than a fatal error because I could handle the issue myself in my own code in whatever way makes sense for my project, especially if I allow users to specify their own locales. I may want to fall back to something other than English, for example.

At the very least, a fatal error isn't a good thing in any case.

[jenssegers]

I would rather have a setFallback or setFallbackLocale so that people can choose to enable this functionality. Could also make it use 'en' by default, but at least people have a way of changing the fallback this way :)

[danhunsaker]

In that case, setFallbackLocale is probably the better bet, name-wise, in case other fallbacks are introduced for other things later on. A default fallback does seem wise, though, given the fatal error we get otherwise.

[zhaofengli]

Great! Adding that.