v1.2.1: Multi-Semester Ready

No real functional changes in the bot, but some minor changes that warrant a new minor version number

• Analysis now differentiates between different semesters
• Folder structure now differentiates between different semesters
• Changelog-style messages updated to differentiate between different semesters
• Analysis can now be run from different timezones without becoming wrong
• Added support for /jetze@MensaQueueBot] messages
• New simplified data download scripts from deployment
• README updates
• And minor changes