ScanDir 的大小寫統一

　
將 ScanDir 處理的名稱統一轉成小寫，便利副檔名過濾。
壞處是：對中文路徑名的誤判度再次加大...

    void setup (TClass* ref, PFT enter, PFT scan, char* sFilter=0)   
    {
        char* c;
        obj               = ref;
        process_enter     = enter;
        process_each_scan = scan;
        nFilter           = 0;
        if (sFilter)
            for (char* p=sFilter; *p; ++p)
                if (*p == '.') {
                    strncpy (filter[nFilter], sFilter, p-sFilter);
                    filter [nFilter][p-sFilter] = '\0';
                    for (c=filter[nFilter]; *c; ++c)
                        if ('A'<=*c && *c<='Z') *c^=('A'^'a');
                    nFilter++;
                    sFilter = p+1;
                }  
    }
    bool match_filter ()                            //過濾副檔名
    {                                               //若副檔名存在 filter
        int   i;                                    //集合中則回傳 true
        static char fname[128];
        char* s = curFile->name;
        char* p = s + strlen (s) - 1;

        for (i=0 ;p>s && i<8; ++i, --p)
            if (*p == '.') {p++; break;}
        if (i > 0) {                                //副檔名至少要有一個字元
            strcpy (fname, p);
            for (char* c=fname; *c; ++c)            //轉成小寫 
                if ('A'<=*c && *c<='Z') *c^=('A'^'a');

            for (i=0; i<nFilter; ++i) 
                if (strcmp (fname, filter[i]) == 0)
                    return true;
        }    
        return false;
    }