m_joinflood Make the code friendlier, unset +j when the module is unloaded

See 21c3232b8e0bb41727f2d65a0b2d5304587cf6be and fae560cddc389b88c9cd34afdccf9035f4d11c5b
Get rid of strlcpy(), strlcat(), charlcat() and charremove()