Allow user to choose whether to see the results in context or not

[harisont]

Right now, text mode is the only way to see results in context, while CoNNL-U and tree mode only show the extracted subtrees:

vs

It would be much nicer if the user could choose between one or the other in all three modes.
If the user chooses to see matches in context, the same highlighting strategy currently used in text mode could be applied to CoNLL-U (easy) and tree (slightly more difficult) output.