Add Discord-style emoji support to chat + extras

Replaces emojis entered in Discord-style :name: format with the actual emoji as you type.
Includes a full map of name to emoji characters as a static unordered map. This map was extracted from Discord's JavaScript.
Rewrites cursor handling and other bits of code in order to support the multi-byte nature of emojis.
Implements the normal functionality of Home and End keys (start and end of line) while typing chat messages.
Implements ctrl+left/right for navigating left/right by word instead of character.
Fixes some small bugs with text rendering

Demo video of added features:

SnowyMouse / chimera