Improve Finnish hyphenation

[akx]

This PR switches Lang::Finnish to hyph-fi-x-school patterns, replacing the Saarinen hyph-fi rules that haven't been updated in... a while. They're older than me, originally...

The school rules follow the simpler syllabification rules taught in Finnish schools and, crucially, include systematic vowel-sequence break rules (i1o, e1a, o1a, …) that the old set omitted.

This both improves accuracy for Finnish as well as shrinks the embedded trie. I originally noted this with the word "äänioikeus", which was mishyphenated as ää-nioi-keus (when ää-ni-oi-keus is correct).

The new set was validated mechanically against Voikko, which is a full morphological hyphenator for Finnish, with a 109K word list.

metric	old (Saarinen)	new (school)
exact-match per word	86.00%	95.69%
recall	95.15%	98.67%
precision	99.08%	98.85%

For this set, 7 540 native words become newly correct and 316 become newly wrong, which translates to a roughly 24:1 improvement.

The residual errors can't be resolved by Liang patterns:

• Finnish is full of compound words; you'd need to know "aamunavaus" is a compound word "aamun-avaus" to correctly automatically hyphenate it at the compound word boundary.
• Some words in the test set are loanwords or foreign names, which would require linguistic analysis ("this word is actually not Finnish, hyphenate it differently").

The old hand-written Saarinen file had a bunch of hand-written patterns (see the comments in the file linked above) that technically help keeping clusters together in certain internationalisms (that would have been common in 1980-1990 TeXnical writing). However, for general use, they break things (499 words fixed c.f. Voikko, 1 976 words broken). So, no use adding them back.