Add sentences counting

[brogol]

Hello,

I needed to count sentences for my usage, I think it could be interesting for someones.
Here the code I've used, maybe not perfect but you get the spirit:

sentences: trimmed ? (trimmed.match(/[.?!…\n]+./g) || []).length + 1 : 0

[RadLikeWhoa]

Added this as part of version 2.1.0 (https://github.com/RadLikeWhoa/Countable/releases/tag/v2.1.0). I decided not to split sentences at newlines, though.