Rainbow_csv interferes with syntax of BufExplorer

[Hans-Guenter]

The hack introduced in rainbow_csv#handle_buffer_enter() of the plugin rainbow_csv on July 1st 2019 (ugly hacks) disables all syntax elements when reentering the Bufexplorer buffer by executing the BufEnter autocommand and therein

execute "set ft=" . ft_hack

because Bufexplorer has not defined a FileType autocommand.

An easy fix for me was to add the autocommand

autocmd FileType bufexplorer call s:SetupSyntax()

to the augroup BufExplorer and remove the call s:SetupSyntax() from the function s:DisplayBufferList().