helper

function containsValue (tab, val)
    for index, value in ipairs(tab) do
        if value == val then
            return true
        end
    end

    return false
end

function math.clamp(value, low, high)
    return math.min(math.max(value, low), high);
end

function string:split(delimiter)
  local result = {};
  local from = 1;
  local delim_from, delim_to = string.find( self, delimiter, from  )
  while delim_from do
    table.insert( result, string.sub( self, from , delim_from-1 ) )
    from  = delim_to + 1
    delim_from, delim_to = string.find( self, delimiter, from  )
  end
  table.insert( result, string.sub( self, from  ) )
  return result
end