Fix inline replies breaking mentions

Created by: VelvetThePanda

Summary

#704 brought inline replies to the library, and a major oversight was made. This fixes #897 (closed)

Details

This PR Fixes a bug introduced by yours truly where setting inline reply to not mention would also make everything else not mention. This behavior has been corrected.

Changes proposed

Adds new repliedUser parameter to DiscordMentions.cs, and uses that for determining whether to mention a user or not

Notes

This seems to work in 99% of test cases.