Rhyme update!

Here's the rhyme update, giving you all sorts of rhyming power! It adds different rhyme modes, which will work with the rhyme carrier to generate rhymes of varying degrees of correctness. You can use the `[rhymemode]` function to select your modes. Separate multiple modes with a space (ex. `[rhymemode: perfect forced slant_rhyme]`). Here are the valid rhyme modes:

* `perfect` - What everyone thinks of when they think of a rhyme. lime / sublime, picky / icky. This means that the first vowel sound after the primary stress and everything after it matches.
* `weak` - Where the penultimate syllable is stressed and the final syllable rhymes. hammer / carpenter, coffin / raisin.
* `syllabic` - The last syllables rhyme. senator / otter, knuckle / tentacle
* `semirhyme` - Where the words would rhyme if not for the last syllable. broom / broomstick, viking / flamingo
* `forced` - If you really, really need something that rhymes, try this. It's a bag of worms, but it can be funny.
* `slant_rhyme` - The ending consonants match. trunk / skunk, rant / ant.
* `pararhyme` - All the consonants match. tuna / teen, man / money, boat / bat.
* `alliteration` - The beginning consonants match. leg / lady, dog / dude.