emoji.lua: Add rofl=😂 and other improvements

    Add rofl=😂, shut up linter/luacheck
    Linter: functions explicitly go to _G or are local
    Moved emoji table to the end and its divided by line (diffs were too big)
    str2emoji(): simplify pattern
    str2emoji(): gsub points to table instead of function (faster)
    use string.find in conditionals not string.match
    Use function alias for functions that all do the same thing
    tabs search entire string :token: and look/replace with approximations

Author: Nomarian