Request: Better naming scheme for auto generated filenames

[scandic]

Problem:
I.e. when using the autosplit function (CLI) the destination file name is specified with the --save switch. Then the first file is named exactly like provided on the command and al other files just get a 01-99 suffix attached to the file name. This is very uncomfortable for scripting/automatization purposes. Also a maximum of 100 chunks isn't sufficient for larger projects.

Solution:
Raise the number of max. chunks plus add possibility to add placeholders to the --save argument, i.e. filename_#.mp4 for filename_0001.mp4 to filename_9999.mp4 in addition to the current naming schema to keep backward compatibility.