YEP

gistfile1.lua

function HURR(sub,sel,act)
  for x = 1,#sub do
    local line = sub[x]
    if line.class == "dialogue" then
      if line.text:match("^{.-\\i1.-}") and line.text:match("{.-\\i0?.-}$") then
        line.text = line.text:gsub("{\\i[01]?}","")
        line.text = line.text:gsub("^({.-)\\i1(.-})","%1%2")
        line.text = line.text:gsub("({.-)\\i0?(.-})$","%1%2")
        line.style = line.style.." italic"
        sub[x] = line
      end
    end
  end
end

aegisub.register_macro("Strip Italics","HURR DURR", HURR)