Adds the ability to randomly seed the inlineipsum

This is my first attempt at extending inline ipsum to let you use a fixed seed for random generation. This would be useful when doing AB comparisons so that you get the same text across samples.

I'm not sure I love the syntax yet. I'd like to make it so that you call .seedRandom("myseed") on a single line, it automatically resets it without having to call .seedRandom() on the next call.

Perhaps I should overwrite _getWords, _getSentences, and _getParagraphs as well to make them call seedRandom() after they call _lorem.createText() ?