Bug fixes

[doluk]

Fixes:

• The broken meta or title tags caused by utf8 emojis in the channel or server name. Those were replaced with images like emojis in messages, but due to the " in the new text the tags were not recognized correctly
• The issue when embedding the attachment data directly into the transcript that the code would break trying to figure out the file icon for the attachment as the proxy_url wouldn't contain any .fileextension anymore. It now falls back to the filename in such cases. Furthermore the IndexError should be avoided by rsplit in combination with indexing with -1 instead of 1.

Improves:

• Refactoring a part of the the message parsing logic of references to make it more readable and easier maintainable.