Feature Request: Rename preview and introduce traditional preview

[MarkowEduard]

With the current version preview is showing where a piece will land. Thankfully, this can be disabled with the command line option "-n". Nevertheless, this is a feature not available with most of the other implementations and, even more importantly, not available with the classic version of the game. OTOH, the classic preview function is to show which piece will be given next. This feature cannot be disabled with the current version and the next piece appears before the soon to be current piece is visible. To rephrase that: The next piece which shows up in the frame at the top right is in fact the piece after the next piece because it is displayed even before the soon to be current piece is visible. Therefore: it would be an improvement to having an option to disable this kind of preview and if not disabled to only show the next piece after the soon to be current piece is already visible in the field of operation.