Character Counter (Chars.pm) - More triggers, quoted strings and better tests

Trying to get the DuckDuckHack experience first hand! I see that some of the docs are based on this instant answer, so no worries if you would prefer to leave the IA as it is.

Includes a bunch of tests for the triggers and the different expected behaviors. All currently passing.
@moollaza But the devs would still have to install an extra module on their system since `duckduckgo/duckduckgo` doesn't use it yet?

I guess we can add that in to `Meta/Helper.pm`, but while we haven't, this regexp is perfectly fine for this PR.