Fix compilation on 32-bit systems storesession.h was declaring fields as std::atomic<uint64_t>, a type not avaiable on 32-bit systems. However, the values stored in these fields were only used as input to QProgressDialog, which takes int, not uint64_t. So the fields could just as well be std::atomic<int>. Also, added code to scale the progress values down if they would not fit in an int. (This would have been needed even if the fields were to remain as uint64_t.)