This pull request consists of:
1) Adding telegram handle to user table
2) Adding error handling:
a) If user signs up for the same event twice, delete and add events_joined
b) If user signs up with the same username and NUSNETID, reject initialization
c) If user signs up with the same telegram_id, delete and add user
d) If user keys in same event name while adding event, error message appears
This pull request consists of: 1) Adding telegram handle to user table 2) Adding error handling: a) If user signs up for the same event twice, delete and add events_joined b) If user signs up with the same username and NUSNETID, reject initialization c) If user signs up with the same telegram_id, delete and add user d) If user keys in same event name while adding event, error message appears