Code improvements

Changes

• Using cookie to keep information about scroll
• All reserved words "var" were replaced with "let" or "const"
• "use strict" mode
• Added dates to messages
• Small optimizations and improvements

Avatars, auto-loading, birthdate

Changes

• Auto-genering avatars for every user
• Auto-loading messages with scroll + loading animation
• Age -> birthdate
• Limit message length - 1000 symbols
• GitHub buttons on footer
• Small changes and improvements

Fetching data

Changes

1. XMLHttpRequest -> fetch on all pages
2. Beautiful error notifications
3. Chat messages about registration a new user
4. Removed user login and logout messages
5. Minor design changes on the profile, settings and chat pages and in the navbar and footer
6. Combine some of the functions related to requests to friends
7. General code improvements

Notification

We've added notifications about new friend requests, accepting friend requests, and deleting them from friends