Add new options and fixes

[superbonaci]

Changes to videodownload:

• Add -K option to keep complete cache folder
• Add -k option to keep cache folder but .ts parts
• Make -o optional to skip converting output.ts to another file
• Add -F to skip free space check
• Update space check function but not accurate in certain cases. A few samples included in comment.

Other:

• Explain better crop beginning and crop ending
• Add a newline after 100% progress to VideoDownloader.cs and TsMerger.cs, other modes may need this. This is to put the shell prompt in a new line after TwitchDownloaderCLI ends, may happen in some cases only.

[superbonaci]

New PR soon.