Add tests for RiTa.randomWord matching stress/phoneme

[dhowe]

Test against full, partial and regex matches for both phonemes and stresses

[dhowe]

• [x] Now both options should work (either a pattern [string or regex] as first arg, or a regex property in the options object) - please add tests as needed for all options in randomWord() and search(), with phones, letters and stresses.
• [x] Please also check documentation mentions first option as a pattern (string or regex) for randomWord() and search() - need to worry about documenting regex.options for now (I've saved your docs in the PR for later )

Note that these 2 functions should work the same in Java/JS and there are no longer any special options in Java (eg pos/numSyllables as first argument)