add a string_util::tolower() and string_util::toupper() for converting string case
add a string_util::tolower() and string_util::toupper() for converting string case


kongr45gpen/bzflag-import-1,kongr45gpen/bzflag-import-1,kongr45gpen/bzflag-import-1,kongr45gpen/bzflag-import-1,kongr45gpen/bzflag-import-1,kongr45gpen/bzflag-import-1