Changes

• fix: sanitize filenname before writing the NZB file (closes #35)
• refactor: use Terminal=true in the linux desktop file to open user's default terminal and run the app executable directly (should fix the issue where nzb-monkey-go does not start on some linux distributions)(closes #34)
• fix: provide NZBLNK argument in single quotes in the linux desktop file in order to avoid problems with special characters in the NZBLNK interpreted by the shell