squirrelmail security and bug fix update

1.4.8-21.0.2.el5 - remove Redhat splash screen images from source 1.4.8-21.0.1.el5 - remove Redhat splash screen images - add README instead of README.RedHat 1.4.8-21 - change charset for zhCN and zhTW to utf-8 508686 1.4.8-20 - fix header encoding issue 241861 - fix code producing warnings in th...