cs: fix bugs
cs: improve regex layout and readability

m/...$/  → m{ ... $}x
s/...$// → s{ ... $}{}x
add case folding and normalization (NFC) of words

this is now the first step of stemming
bg: improve regex layout and readability

s/...$// → s{ ... $}{}x
make code more consistent
fa: sort strings in regexes and remove duplicates
update dependencies and TODO