more reply reactions and match whole words, replace Unicode library

etc/utf8

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+Subproject commit 17f4e009a22fb2f2e6ad316a05b2cca8e071fc3b

etc/utf8.lua

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--- Unicode library
-
-local pattern = '[%z\1-\127\194-\244][\128-\191]*'
-
--- helper function
-local function posrelat(pos, len)
-  if pos < 0 then
-    pos = len + pos + 1
-  end
-  return pos
-end
-
-local utf8 = {}
-
--- THE MEAT
-
-function utf8.map(s, f, no_subs)
-  local i = 0
-
-  if no_subs then
-    for b, e in s:gmatch('()' .. pattern .. '()') do
-      i = i + 1
-      local c = e - b
-      f(i, c, b)
-    end
-  else
-    for b, c in s:gmatch('()(' .. pattern .. ')') do
-      i = i + 1
-      f(i, c, b)
-    end
-  end
-end
-
--- THE REST
-
-function utf8.chars(s, no_subs)
-  return coroutine.wrap(function()
-    return utf8.map(s, coroutine.yield, no_subs)
-  end)
-end
-
-function utf8.len(s)
-  return select(2, s:gsub('[^\128-\193]', ''))
-end
-
-function utf8.replace(s, map)
-  return s:gsub(pattern, map)
-end
-
-function utf8.reverse(s)
-  s = s:gsub(pattern, function(c)
-    return #c > 1 and c:reverse()
-  end)
-  return s:reverse()
-end
-
-function utf8.strip(s)
-  return s:gsub(pattern, function(c)
-    return #c > 1 and ''
-  end)
-end
-
-function utf8.sub(s, i, j)
-  local l = utf8.len(s)
-
-  i = posrelat(i, l)
-  j = j and posrelat(j, l) or l
-
-  if i < 1 then i = 1 end
-  if j > l then j = l end
-  if i > j then return '' end
-
-  local diff = j - i
-  local iter = utf8.chars(s, true)
-
-  for _ = 1, i - 1 do iter() end
-  local c, b = select(2, iter())
-
-  if diff == 0
-  then return s:sub(b, b + c - 1) end
-
-  i = b
-  for _ = 1, diff - 1 do iter() end
-  local c, b = select(2, iter())
-
-  return s:sub(i, b + c - 1)
-end
-
--- ADDITION
-
-require 'etc.utf8data'
-
-function utf8.upper(s)
-  return utf8.replace(s, utf8_lc_uc)
-end
-
-function utf8.lower(s)
-  return utf8.replace(s, utf8_uc_lc)
-end
-
-return utf8