Automatically continue blockquote on automatically wrapped lines

[robertrosman]

When writing long lines in a blockquote that are automatically wrapped, they are not continued inside a blockquote. Inserting manual line breaks work as expected. Example:

> Short lines work
> like this.
> 
> Can even insert a new line down here.

> But when trying to insert a long line that is automatically wrapped, it doesn't
seem to work. No ">" is inserted at the beginning of the new line.

[shirosaki]

That seems to be introduced for bullet insertion feature.
5cd2223

https://github.com/plasticboy/vim-markdown/blob/master/indent/markdown.vim#L11

[shirosaki]

Here is a solution.

In .vimrc:

function! s:ChangeFormatOption()
    if &filetype == 'markdown'
        if getline(line('.')) =~ '^>'
          setlocal formatoptions+=c
        else
          " Do not automatically insert bullets when auto-wrapping with text-width
          setlocal formatoptions-=c
        endif
    endif
endfunction

augroup MkdFormatOption
    autocmd!
    autocmd CursorMovedI *.m* call s:ChangeFormatOption()
augroup END