Useful additions മ◡മ

• Add tag <-> emoticon link editor
• Show tag suggestions under search bar
• Remove redundant menu shown on long press on emoticon, instead use a unified bottom sheet for all operations, thanks to comment for suggestion. Fixes #1
• Add Material You theming
• Add Settings page
• Add export/import of emoticons and tags
• Add About page
• Internal change: use SQLite db as initial emoticons source instead of CSV+JSON
• Bundle Noto Sans ttf font explicitly to support more glyphs (WIP)