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)

Can you split this and comment on each line for readability?

```perl
my $frequencySpectrumQR = qr/^(?<quantity>[\d,]+(\.\d+)?)                    # Comment 1
                             ((?<factor>k|kilo|m|mega|g|giga|t|tera)?        # Comment 2
                             ...
                             /x;