Adding opportunity to sort by filename or ID3-Tag or Track-No.

[MojitoJoe1813]

Please check my PR properly.:

This is a pull request addressing an issue I reported: #86 .
Please note: I did not work with C# before - Therefore I forked your repo at first. I did not work on any other code than TrackSortDialog, so I do not know the full picture of this application. And because of that and despite successful testing the TrackSortDialog myself multiple times for now, this code might be incorrect or lead to unknown sideeffects I did not encounter myself. Anyway it can be used to implement the intention correctly, I guess.

• Update to .NET v4.8.1
• Removed the filter on reading only MP3-files where Track is assigned. Reason: I can't see the reason for that filter, however, reading the Track seems not to work correctly with the ID3-Library used. ID3v2.3 Tags created by common MP3-Tag-Editors don't seem to work regarding track data. See reported issues at the ID3 library.
• Added an additional column (SubItem) to show the track no. which is read from the ID3-Tag.
• Added a regex-filter to remove "\0" from ID3-Tag-Data used. Reason: Some ID3-Tags (written by common MP3-Tag-Editors) end with "\0" when read by the library used here and by this break the concatenation of artist & title.
• Added a ListViewItemComparer class to add sorting by columns. Reason: Adding files with track-data not properly processed by the ID3-library lead to incorrect order. I wanted to be able to sort the tracks not only inconveniently by the buttons "Up" or "Down" but also easily by file name or ID3-Tag. This class now allows to sort by the column by just clicking the column header.