Add visual to Frequency Spectrum goodie

Re #300, adds visual (inline SVG) for electromagnetic and/or audible frequency ranges.
![image](https://cloud.githubusercontent.com/assets/726198/3488558/cb77b122-04ef-11e4-9899-26da233c6315.png)

@mwmiller unfortunately not, but the triggering could always be improved (though that would require some serious testing). Originally I had discussed and considered a more granular approach to trigger words but right now the way it works is by splitting up the string on spaces and special chars (eg. "_", "-", ":") and then checks if any of those are trigger words but as you can see it doesn't do any substring matching.

Perhaps that's a new type of trigger we should consider, `endword` or `startword`, that does exactly that? I'm not sure how useful it would be (we haven't really needed something like that before...) but it's totally possible.

Alternatively being able to specify for the triggers what character it should be separated on might also be useful and beneficial, eg:

```perl
triggers splitOn => qr/\d+/;
triggers any => "hz","khz","mhz","ghz","thz";

# 6hz => ["6", "hz"] => Match on "hz"!
#winning!
```

I suppose the easiest fix though is to just use a regex trigger