Return a default meaningful text to replace NotSupportedException

[yufeih]

There are 2 ways for TimeAgo to throw NotSupportedException:

1. The culture info is not supported, in this case we can fallback to English
2. The time is exactly now or somewhere in the future, in this case we can say "in 10 hours" just like in momentjs.com

[NickStrupat]

I'm happy to add an overload or configuration to specify a default CultureInfo, but I don't think falling back to English silently is a good fit here.

I really like the idea of adding the ability to work with DateTimes in the future. I cut that out of scope originally, but I'm into the idea now.

[NickStrupat]

Thanks for your pull requests, btw!

[yufeih]

Fallback to en (or the default culture) is all about making sure no exceptions are throwing calling TimeAgo method. Because the use case of TimeAgo is more like ToString, and the best practices to override System.ToString is

Your ToString override should not throw an exception.

[NickStrupat]

I like your reasoning. I'm sold. I'll try to get that change done this week and start on the 'from now' work hopefully.