enhance match display in default output

[thatbudakguy]

it's difficult to interpret results without viewing the match in at least some document context. we certainly don't need the entire document, but a few characters on either side would probably help. we can also highlight the actual match portion in color and/or bold the portions that are graphic variants.

• add optional context on either side of match (see comparable grep options -B and -A)
• add optional highlights for insertions, substitutions, and variants using text/background color, bold, italics, etc. (--color)
• replace newlines in output with ⏎ or a similar indicator
• allow displaying the actual phonemes along with the text

it might be worth writing a match.pretty() method or similar to encapsulate this functionality. the best way to do it is probably by removing this concern from Match entirely, and writing a Formatter class that handles the display of matches.

note that writing to a file should disable --color, since the output will otherwise include a lot of unwanted control characters.