Well... the program just did something that I might actually call 'working' at this point. It's still very unoptimized (loading the tree of dictionary words takes longer than it needs to, and the number of comparisons it needs to do to a string is exponential), but I have ideas to get both of those working better.

Yeah, I was hoping to be more productive tonight, but I kept making dumb blunders. Anyway, progress is progress.

Here's the program's final output:

thisisplaintext has 3 words in it. vjkukurockovgzv has 1 words in it. uijtjtqmbjmufyu has 0 words in it. wklvlvspdlpwhaw has 0 words in it.

(it ignores 'is' because it only has two characters; at the moment it ignores words of two characters or less to speed up the processessing)