IRC 2 PSO2 code: use replace error mode to make it safe

    let replace bad unicode with U+FFFD and not return 'ValueError'
Prework for Pthon's re

   move table string replace to an alone function
Keep PSO2 Text clean

   handle all contro chars from 0x00 to 0x1F
Merge pull request #53 from alama/cleanup-IRC2PSO2

Let clean up the IRC chat of control chars