arogue5: fix the crash when checking prices in shops. A buffer called curpurch, which stores a description of an item in a trading post which the player might be interested in, was only 15 bytes. It was overflowing into oldrp, a room pointer, leading to segfaults. The size of curpurch has been increased to LINELEN*2, which matches the size of prbuf, which is returned by inv_name and then strcpy()'d to curpurch. As long as nothing overflows prbuf it should be safe now. NOTE that this breaks savefile compatibility.