Support for extracting positional template parameters

Sometimes we want to extract the values of template parameters which are positional (just designated by positions, not parameter names).

For instance:
{{location|60.165787|24.9460811}}
(taken from Sandra's parsing wishlist).

We could want to extract the first and second values in the template. One possible way would be to extend the functionality of the findTemplateValues() function that we already have, so that it accepts a number as third argument, like this:

findTemplateValues(wikitext, 'location', 1)

On the sample wikitext above, it would return ['60.165787'].

When running findTemplateValues(wikitext, 'location', 2) you would get ['24.9460811'].