Editing codes (see description)

[lck3141592654]

1. Optimize width of characters for Chinese
2. Fix incorrect information to optimize width of each characters in updater/README.md
   In original, setGoodFontSize() is not called so you cannot optimize width of each characters by adding a function to setGoodFontSize()
3. Update all_char_zh.txt
4. Raise opacity threshold in char image generation in order to reduce blurry edges on small canvases for non-latin languages.
5. Add remove_duplicate_dialogue.py to remove duplicate English entries from 'dialogue' sheet in transcript_{lang}.xlsx.
6. Add a quick guide with flowchart and modify UI in updater/README.md