Automatically identify and convert "full-width" versions of Markdown syntax

[chen-yingfa]

When editing a Chinese document, it can be tedious to change between full-width and half-width (全角 and 半角) characters for using Markdown syntax, and I wish that the editor could automatically identify the full-width versions of Markdown syntax and convert them into half-width versions. E.g., when entering ￥￥ and a next line, the editor should convert it into $$ and start a math block. The same applies to ···{language} -> ```{language}.

[1943time]

Code fence and block level formulas can add this kind of transformation, but other elements will not be added temporarily because i don't want to add too much transformation black magic yet.